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Mathematical reasoning - class-XI

Description: mathematical reasoning
Number of Questions: 105
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Tags: business maths similar triangles proofs in mathematics mathematical reasoning discrete mathematics mathematical logic maths principle of mathematical induction
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Without using truth , whether
$\left[ {p\Delta \left( { \sim q\Delta r} \right)} \right]V\left[ { \sim r\Delta  \sim q\Delta p} \right] \equiv p$

  1. True

  2. False


Correct Option: B

Solve it:-
$\left( {p \to q} \right) \to [\left( { \sim p \to q} \right) \to q]$

  1. Tautology

  2. Contradiction

  3. Contingent

  4. Not statement


Correct Option: A
Explanation:
$Y=\left( p\longrightarrow q \right) \longrightarrow \left[ \left( \sim p\longrightarrow q \right) \longrightarrow q \right]$
Method : TRUTH TABLE [  ALWAYS PREFERABLE]

 $p$  $q$  $p\longrightarrow q$  $\left( \sim p\longrightarrow q \right) $  $\left[ \left( \sim p\longrightarrow q \right) \longrightarrow q \right]$  $Y$
 $1$  $0$  $0$  $1$  $1$ $1$ 
 $1$  $1$  $1$  $1$  $1$  $1$
 $0$  $0$  $1$  $0$  $1$  $1$
 $0$  $1$  $1$  $1$  $1$  $1$
As the result is always TRUE $\left(i.e. 1\right)$;
$\left( p\longrightarrow q \right)\longrightarrow \left[ \left( \sim p\longrightarrow q \right) \longrightarrow q \right]$ is Tautology.

A. Tautology



















Which of the following is true

  1. $a _{r}=a _{n-r}$

  2. $a _{2r}=a _{n-r}$

  3. $a _{r}=a _{2n-r}$

  4. $None\ of\ these$


Correct Option: A

Let $p$ and $q$ be two propositions given by
$p$ : The sky is blue.
$q$ : The milk is white.
Then $p\wedge q$ will be

  1. The sky if blue or milk is white

  2. The sky is blue and milk is white

  3. The sky is white and milk is blue

  4. If the sky is blue then milk is white


Correct Option: B
Explanation:

$p \wedge q$ means statement p and q
=> The sky is blue and  milk is white.

Let $p$ and $q$ be two propositions. Then the contrapositive the implication $p\rightarrow q$

  1. $\sim q\rightarrow \sim p$

  2. $\sim p\rightarrow \sim q$

  3. $q\rightarrow p$

  4. $p\leftrightarrow q$


Correct Option: A
Explanation:

the contrapositive of $p\to q$ is $\sim q\to \sim p$

Negation of $(\sim p\rightarrow q)$ is ________________.

  1. $\sim { p }{ \wedge }\sim q$

  2. $\sim \left( p\vee q \right) \vee \left( p\vee \left( \sim p \right) \right) $

  3. $\sim \left( p\vee q \right) \wedge \left( p\vee \left( \sim p \right) \right) $

  4. $\left( \sim p\vee q \right) \wedge \left( p\vee \sim q \right) $


Correct Option: A

$p \wedge ( q \vee \sim p ) =?$

  1. $p \vee q$

  2. $p \wedge q$

  3. $p \rightarrow  q$

  4. none of these


Correct Option: B

$( p \wedge q ) \vee ( \sim p \wedge q ) \vee ( \sim q \wedge r ) =? $

  1. $q \vee r$

  2. $q \wedge r$

  3. $q \rightarrow r$

  4. none of these


Correct Option: B

If $p$ is false, $q$ is true, then which of the following is/are false?

  1. $\sim (p\Rightarrow q)$

  2. $\sim p$

  3. $\sim p\Rightarrow q$

  4. $\sim q$


Correct Option: A,D
Explanation:
 $p$  $q$  $p\Rightarrow q$ $\sim \left( p\Rightarrow q \right) $  $\sim p$  $\sim q$   $\sim p\Rightarrow q$
 F  T  T  F  T  F  T

Here we see that $\sim \left( p\Rightarrow q \right) $  and $\sim q$  are false

$p$: He is hard working.
$q$: He is intelligent.
Then $ \sim q\Rightarrow\sim p$, represents

  1. If he is hard working, then he is not intelligent.

  2. If he is not hard working, then he is intelligent.

  3. If he is not intelligent, then he is not had working.

  4. If he is not intelligent, then he is hard working.


Correct Option: C
Explanation:

p:she is hardworking
q:she is intelligent

~p:she is not hardworking
~q:she is not intelligent

~q=>~p 
means She is not intelligent implies she is not hardworking
Hence, Option C

$p:$ He is hard working.
$q:$ He will win.
The symbolic form of "If he will not win then he is not hard working", is

  1. $ p\Rightarrow q$

  2. $ (\sim p)\Rightarrow (\sim q)$

  3. $ (\sim q)\Rightarrow (\sim p)$

  4. $ (\sim q)\Rightarrow p$


Correct Option: C
Explanation:

Given $p:$ He is hard working

and $q:$ He will win
we get $\sim p:$ He is not hard working

and $\sim q:$ He will not win
Now the given statement in the question is "If he will not win then he is not hard working" which means 
"If he will not win then he is not hard working"
For this conditional statement, the symbolic form is $\left( \sim q \right) \Rightarrow \left( \sim p \right) $

Simplify $(p\vee q)\wedge(p\vee\sim q)$

  1. $p$

  2. $\sim p$

  3. $\sim q$

  4. $q$


Correct Option: A
Explanation:

$(p\vee q)\wedge (p\vee \sim q)$
$=p\vee(q\wedge \sim q)$ (distributive law)
$=p\vee 0$ (complement law)
$=p$ ($0$ is indentity for v)

The negation of the statement "No slow learners attend this school," is:

  1. All slow learners attend this school.

  2. All slow learners do not attend this school.

  3. Some slow learners attend this school.

  4. Some slow learners do not attend this school.

  5. No slow learners do not attend this school.


Correct Option: C
Explanation:

The negation is : It is false that no slow learners attend this school. Therefore, some slow learners attend this school.

Dual of $( p \rightarrow q ) \rightarrow r$ is _________________.

  1. $p\vee (\sim  q\wedge r)$

  2. $p\vee q\wedge r$

  3. $p\vee (\sim  q\wedge \sim r)$

  4. $\sim p\vee (\sim q\wedge r)$


Correct Option: A

The proposition $(p\rightarrow \sim p)\wedge (\sim p\rightarrow p)$ is a

  1. tautology.

  2. contradiction.

  3. neither a tautology nor a contradiction.

  4. tautology and contradiction.


Correct Option: B
Explanation:

 $p$ $\sim p $  $p\rightarrow \sim p $ $\sim p \rightarrow p$  $(p\rightarrow \sim p) \wedge(\sim p\rightarrow p)$ 

A contradiction.

Negation of the statement $p:\dfrac {1}{2}$ is rational and $\sqrt {3}$ is irrational is

  1. $\dfrac {1}{2}$ is rational or $\sqrt {3}$ is irrational

  2. $\dfrac {1}{2}$ is not rational or $\sqrt {3}$ is not irrational

  3. $\dfrac {1}{2}$ is not rational or $\sqrt {3}$ is irrational

  4. $\dfrac {1}{2}$ is rational and $\sqrt {3}$ is irrational


Correct Option: A

P: he studies hard, q: he will get good marks. The symbolic form of " If he studies hard then he will get good marks "is_____

  1. $\sim q\Rightarrow p$

  2. $p\Rightarrow q$

  3. $\sim p\vee q$

  4. $p\Leftrightarrow q$


Correct Option: B

Disjunction of two statements p and q is denoted by

  1. $p \leftrightarrow q$

  2. $p \rightarrow q$

  3. $p \leftarrow q$

  4. $p \vee q$


Correct Option: D

An implication or conditional "if p then q "is denoted by

  1. $p \vee q$

  2. $p \rightarrow q$

  3. $p \leftarrow q$

  4. None of these


Correct Option: B

The truth values of p, q and r for which $(pq)(∼r)$ has truth value F are respectively

  1. F, T, F

  2. F, F, F

  3. T, T, T

  4. T, F, F


Correct Option: C

 The negation of the compound proposition $p \vee (p \vee q)$ is

  1. $(p\wedge ∼q)\wedge ∼p$

  2. $(p\wedge ∼q)\vee  ∼p$

  3. $(p\wedge ∼q)\vee ∼p$

  4. none of these


Correct Option: A

Given, "If I have a Siberian Husky, then I have a dog." Identify the converse

  1. If I do not have a Siberian Husky, then I do not have a dog.

  2. If I have a dog, then I have a Siberian Husky.

  3. If I do not have a dog, then I do not have a Siberian Husky.

  4. If I do not have a Siberian Husky, then I have a dog.


Correct Option: B

$[(p)\wedge q]$ is logically equivalent to

  1. $(p\vee q)$

  2. $[p\wedge(q)]$

  3. $p\wedge(q)$

  4. $p\vee(q)$


Correct Option: D

$∼(p⇒q)⟺∼p\vee ∼q  \, is$

  1. a tautology

  2. a contradiction

  3. neither a tautology nor a contradiction

  4. cannot come to any conclusion


Correct Option: C

Consider the following statements 
$p$:you want to success
$q$:you will find way,
then the negation of $\sim (p\vee q)$ is

  1. you want of success and you find a way

  2. you want of success and you do not find a way

  3. if you do not want to succeed then you will find a way

  4. if you want of success then you cannot find a way


Correct Option: A

Which of the following statements is a tautology

  1. $\left( { \sim p \vee q} \right) - \left( {p \vee \sim q} \right)$

  2. $\left( { \sim p \vee \sim q} \right) \to p \vee q$

  3. $\left( {p \vee \sim q} \right) \wedge \left( {p \vee q} \right)$

  4. $\left( { \sim p \vee \sim q} \right) \vee \left( {p \vee q} \right)$


Correct Option: C

Which of the following is a logical statement?

  1. Open the door

  2. What an intelligent student!

  3. Are you going to Delhi

  4. All prime numbers are odd numbers


Correct Option: D
Explanation:

The above $3$ statements are basic statements.

But the $4$ statement is a logical statement.
All prime numbers are odd numbers.

The proposition $\left( {p \wedge q} \right) \Rightarrow p$ is 

  1. neither tautology nor contradiction

  2. A tautology

  3. A contradiction

  4. Cannot be determined


Correct Option: B

The statement $p \to (q \to p)$ is equivalent to 

  1. $p \to q$

  2. $p \to (q \vee p)$

  3. $p \to (q \to p)$

  4. $p \to (q \wedge p)$


Correct Option: B

Which of the following is correct?

  1. $(~p \vee ~q) \equiv (p \wedge q)$

  2. $(p \rightarrow q) \equiv (~q \rightarrow ~p)$

  3. $~(p \rightarrow ~q) \equiv (p \wedge ~q)$

  4. $~(p \leftrightarrow q) \equiv (p \rightarrow q) \wedge (q \rightarrow p)$


Correct Option: D
Explanation:


$~(p \leftrightarrow q) \equiv (p \rightarrow q) \wedge (q \rightarrow p)$ is true, we show it by truth table using boolean expression.

1.$p\rightarrow q$=min(1,1+q-p)
2.$p\wedge q$=min(p,q)
3.$p\leftrightarrow q$=1-|p-q|

Now we draw or make truth table using these operations
L.H.S  

 p  q $p\leftrightarrow q$ 
 1


R.H.S 

p $p\rightarrow q$  $q\rightarrow p$   $(p \rightarrow q) \wedge (q \rightarrow p)$
1  1  1  1
1  0

L.H.S =R.H.S

$~(p \leftrightarrow q) \equiv (p \rightarrow q) \wedge (q \rightarrow p)$

$(p \wedge q) \vee  \sim p$ is equivalent to 

  1. $\sim p \wedge q$

  2. $\sim p \vee q$

  3. $p \wedge q$

  4. $p \vee q$


Correct Option: A

In a certain code language, $'543'$ means 'give my water'; $'247'$ means 'water is life' and $'632'$ means 'enjoy my life'. Which of the following stands for 'enjoy' in that language?

  1. $7$

  2. $6$

  3. $2$

  4. $5$


Correct Option: A

$\sim (p \wedge q)\Rightarrow (\sim p)\vee (\sim p \vee q)$ is equal to

  1. $\sim p \vee q$

  2. $\sim p \wedge q$

  3. $p\vee \sim q$

  4. $p\wedge \sim q$


Correct Option: A

The equivalent of $(p \rightarrow \sim p) \vee (\sim p \rightarrow p)$ is 

  1. $p \vee \sim p$

  2. $T \rightarrow F$

  3. $T \leftrightarrow F$

  4. $p \wedge \sim p$


Correct Option: A

Identify which of the following statement is not equivalent to the others

  1. If $x$ is bass then $x$ is bad.

  2. Boss implies bad,

  3. Bad is necessary condition for bass.

  4. $x$ is boss iff $x$ is bad.


Correct Option: A

Either $p$ or $q$ is equivalent to:

  1. $p \vee q$

  2. $(p \vee \sim q) \vee (q \wedge \sim p)$

  3. $(p \vee \sim q) \wedge (q \vee \sim p)$

  4. none


Correct Option: A

Equivalent statement of ''If $x\in Q$, then $x\in T$'' is
$x\in Q$ is necessary for $x\in l$
$x\in l$ is sufficient for $x\in Q$
$z\in Q$ or $x\in l$
$x\in Q$ but $x\in l$ 

  1. $I$ & $II$

  2. $I,\ II$ & $IV$

  3. $III$

  4. $All$


Correct Option: B

Let  $P , Q , R$  and  $S$  be statements and suppose that  $P \rightarrow Q \rightarrow R \rightarrow P.$  If  $\sim S \rightarrow R,$  then

  1. $S \rightarrow \sim Q$

  2. $\sim Q \rightarrow S$

  3. $\sim S \rightarrow \sim Q$

  4. $Q \rightarrow \sim S$


Correct Option: B

$(p\rightarrow q)\leftrightarrow (q\vee \sim p)$ is - 

  1. Equivalent to $p\wedge q$

  2. Tautology

  3. Fallacy

  4. Neither tautology nor fallacy


Correct Option: A

Let S be a set of n persons such that:(i)any person is acquainted to exactly k other persons in s;(ii)any two persons that are acquainted have exactly $\displaystyle l $ common acquaintances in s;(iii)any two persons that are not acquainted have exactly m common acquaintances in S.Prove that $\displaystyle m\left ( n-k \right )-k\left ( k-1 \right )+k-m= 0.$

  1. $\displaystyle k\left ( k-1-l \right )= m\left ( n-k-1 \right )$ is equivalent to the desired one.

  2. $\displaystyle k\left ( k+1-l \right )= m\left ( n-k-1 \right )$ is equivalent to the desired one.

  3. $\displaystyle k\left ( k-1+l \right )= m\left ( n-k-1 \right )$ is equivalent to the desired zero.

  4. $\displaystyle k\left ( k+1-l \right )= m\left ( n-k+1 \right )$ is equivalent to the desired one.


Correct Option: A
Explanation:

Let a be a fixed element os S. Let us count the triples (a, x, y) such that a, x are acquainted, x, y are acquainted and a, y are not acquainted. Because a isacquainted to exactly k other persons in S, x can be chosen in k ways and for fixeda and x, y can be chosen in $\displaystyle k-1-l $ ways. Thus the number of such triples is $\displaystyle k\left ( k-1-l  \right ).$ Let us count again, choosing y first. The number of persons not acquainted to a equals n-k-1, hence y can be chosen in n-k-1 ways. Because x is a commonacquaintance of a and y, it can be chosen in m ways, yielding a total of $\displaystyle m\left ( n-k-1 \right )$ triples. It is not difficult to see that the equality $\displaystyle k\left ( k-1-l  \right )= m\left ( n-k-1 \right )$ is equivalent to the desired one.

The dual of the statement $\sim p \wedge [\sim q \wedge (p \vee q) \wedge \sim  r]$ is:

  1. $\sim p \vee [\sim q \vee (p \vee q) \vee \sim r]$

  2. $ p \vee [q \vee (\sim p \wedge \sim q) \vee r]$

  3. $ \sim p \vee [\sim q \vee (p\wedge q) \vee \sim r]$

  4. $ \sim p \vee [\sim q \wedge (p\wedge q) \wedge \sim r]$


Correct Option: C
Explanation:

The dual of the statement $\sim p \wedge [\sim q \wedge (p \vee q) \wedge \sim  r]$ is

$\equiv  \sim p \vee [\sim q \vee (p\wedge q) \vee  \sim r]$

Note: For dual of a statement just replace $\vee$ by $\wedge$ and vice versa.

Which of the following is equivalent to $(p \wedge q)$?

  1. $p \rightarrow \sim q $

  2. $ \sim (\sim p \wedge \sim q)$

  3. $ \sim ( p \rightarrow \sim q)$

  4. None of these


Correct Option: C
Explanation:

$p \wedge q \equiv   \sim (\sim p \vee \sim q) \equiv   \sim (p \to \sim q)$

Which of the following is equivalent to $( p \wedge q)$?

  1. $p \rightarrow \sim q$

  2. $\sim (\sim p \wedge \sim q)$

  3. $\sim (p \rightarrow \sim q)$

  4. None of these.


Correct Option: C
Explanation:

$p \wedge q \equiv   \sim (\sim p \vee \sim q) \equiv   \sim (p \to \sim q)$

The equivalent statement of (p $\leftrightarrow$ q) is

  1. $(p \wedge q) \vee (p \vee q)$

  2. $(p \rightarrow q) \vee (q \rightarrow p)$

  3. $(\sim p \vee q) \vee (p \vee \sim q)$

  4. $(\sim p \vee q) \wedge (p \vee \sim q)$


Correct Option: D
Explanation:

$p\rightarrow q \equiv (\sim p\vee q)$

$q\rightarrow p \equiv (\sim q \vee p)$
$\therefore$
$p\leftrightarrow q \equiv (p\rightarrow q)\wedge(q\rightarrow p)$
$\Rightarrow p\leftrightarrow q\equiv (\sim p\vee q)\wedge(p\vee\sim q)$

Which of the following is correct?

  1. $(~p \vee ~q) \equiv (p \wedge q)$

  2. $(p \rightarrow q) \equiv (~q \rightarrow ~p)$

  3. $~(p \rightarrow ~q) \equiv (p \wedge ~q)$

  4. none of these


Correct Option: D
Explanation:

Clearly, the statements $p \vee q$ and $p\wedge q$ cannot be equivalent as they one operator means "OR" and the other operator means "AND".

$p$ $q$ $p\rightarrow q$ $q\rightarrow p$
T T T T
T F F T
F T T F
F F T T

Option B is also incorrect.

$p$ $q$ $p\rightarrow q$ $p\wedge q$
T T T T
T F F F
F T T F
F F T F


Hence, option C is also incorrect.

Option D is also incorrect as
$p \leftrightarrow q=(p\rightarrow q)\wedge (q\rightarrow p)$


Which of the following statement are NOT logically equivalent?

  1. $ \sim (p \vee \sim q)$ and $ (\sim p \wedge q )$

  2. $\sim (p \rightarrow q )$ and $(p \wedge \sim q )$

  3. $(p \rightarrow q) $ and $(\sim q \rightarrow \sim p) $

  4. $(p \rightarrow q )$ and $(\sim p \wedge q)$


Correct Option: D
Explanation:

We make an option wise check for this.

Option A: $\sim \left( p\vee \sim q \right) \quad and\quad \left( \sim p\wedge q \right) $
By application of Demorgan's Law on $\sim \left( p\vee \sim q \right) $ we get, $\sim \left( p\wedge q \right) $ 
So this option is logically equivalent.

Option B: $\sim \left( p\longrightarrow q \right) \quad and\quad \left( p\wedge \sim q \right) $
Again by application Conditional Disjunction rule, we see that this option is also logically equivalent.

Option C: $\left( p\longrightarrow q \right) \quad and\quad \left( \sim q\longrightarrow \sim p \right) $
This is again true by Contrapositive tautology.

Option D:$\left( p\longrightarrow q \right) \quad and\quad \left( \sim p\wedge q \right) $
This is not logically equivalent. 

$(~ p \vee ~ q)$ is logically equivalent to

  1. $(p \wedge q) \vee (p \vee q)$

  2. $(p \rightarrow q) \vee (q \rightarrow p)$

  3. $(\sim p \vee q) \vee (p \vee \sim q)$

  4. $(\sim p \vee q) \wedge (p \vee \sim q)$


Correct Option: D

The statement $\sim (p\rightarrow \sim q)$ is equivalence to ___________.

  1. $(\sim p\vee q)$

  2. $(p\vee \sim q)$

  3. $(\sim p\wedge q)$

  4. $(p\wedge \sim q)$


Correct Option: C
Explanation:

$\sim\left({p} \rightarrow \sim{q} \right)$

We know that,
               $\sim\left({p} \rightarrow {q} \right)={p}\wedge\sim{q}$
          $\Rightarrow\sim\left({p}\rightarrow\sim{q}\right)=\sim{p}\wedge\sim\left(\sim{q}\right)$
                                    $=\sim{p}\wedge{q}$
Hence, $\left(\sim{p}\wedge{q}\right)$ is the correct answer.


Which of the following is always true?

  1. $\sim(p\rightarrow q) \equiv \sim p \wedge q$

  2. $\sim(p\vee q) \equiv \sim p \vee \sim q$

  3. $\sim (p \implies q ) \equiv (p \land \sim q )$

  4. $\sim(p \wedge q) \equiv \sim p \wedge \sim q$


Correct Option: C
Explanation:

$p \implies q \equiv \sim p \lor q  $
$\therefore \sim (p \implies q ) \equiv \sim (\sim p \lor q )$
$\therefore \sim (p \implies q ) \equiv (p \land \sim q )$

Which of the following is/are false?

  1. $p\rightarrow q\equiv\sim p\rightarrow\sim q$

  2. $\sim(p \rightarrow\sim q)\equiv\sim p\wedge q$

  3. $\sim(\sim p\rightarrow\sim q)\equiv\sim p\wedge q$

  4. $\sim (p\leftrightarrow q) \equiv(\sim(p\rightarrow q))\wedge\sim(q\rightarrow p)$


Correct Option: A,B,D
Explanation:

We know that:
$p\rightarrow q \equiv \sim q\rightarrow \sim p$    {By logical equivalences }    
Hence $A$ is false


Now for option $B$
$\sim (p \ \rightarrow \ \sim q)$ $\equiv$ $\sim (\sim p\vee \sim q)=p\wedge q$   [By logical Equivalences ]
Hence $B$ is false

Now for option $C$
$\sim (\sim p\rightarrow \sim q)$ $\equiv \sim (p  \vee \sim q) $  $\equiv \sim p\wedge q$  [By Logical Equivalences]
Hence $C$ is true


Now for option $D$
$\sim (p\leftrightarrow q)$ $\equiv \sim ((p\rightarrow q)\wedge (q\rightarrow p))$ $\equiv \sim (p\rightarrow q)\vee \sim (q\rightarrow p)$
Hence $D$ is false                        [By logical Equivalences]

Which of the following is logically equivalent to $\displaystyle \sim \left (\sim p\rightarrow q\right )$?

  1. $\displaystyle p\wedge q$

  2. $\displaystyle p\wedge \sim q$

  3. $\displaystyle \sim p\wedge q$

  4. $\displaystyle \sim p\wedge \sim q$


Correct Option: D
Explanation:
$\sim p$  $\sim q$  $\sim p \rightarrow q$  $\sim (\sim p \rightarrow q)$  $p \wedge q$  $p \wedge \sim q$   $\sim p \wedge q$   $\sim p \wedge \sim q$  
T
F
F

The values in column 6 and column 10 are same.

Hence, option D is correct.

The dual of the following statement "Reena is healthy and Meena is beautiful" is

  1. Reena is not beaufiful and Meena is not healthy.

  2. Reena is not beautiful or Meena is not healthy.

  3. Reena is not healthy or Meena is not beautiful.

  4. None of these.


Correct Option: C
Explanation:

Let $p$ denote the statement "Reena is healthy" 


and $q$ denote the statement "Meena is beautiful"

Now the given statement is $p\wedge q$

Now the Dual of this statement will be obtained by replacing $\vee$ by 

$\wedge$ and $\wedge$ by $\vee$ and inversing the true value of the statement.

So the Dual of $p\wedge q$ will be $\sim p\vee \sim q$

The statement $\sim p$ will be "Reena is not healthy"

The statement $\sim q$ will be "Meena is not beautiful"

So the dual statement will be $\sim p\vee \sim q$ or "Reena is not healthy or Meena is not beautiful."

The statement "If $2^2 = 5$ then I get first class" is logically equivalent to

  1. $2^2 = 5$ and I do not get first class

  2. $2^2 = 5$ or I do not get first class

  3. $2^2 \neq 5$ or I get first class

  4. None of these.


Correct Option: C
Explanation:

There can be two cases
$2^{2}=5$ $\rightarrow$ first class.
$2^{2}\neq 5$\rightarrow not a first class.
Hence logically equivalent statement will be 
$2^{2}=5$ or $2^{2}\neq 5$ but $2^{2}=5$ statement is equivalent to getting first class.
Hence
First class or $2^{2}\neq 5$.

The statement "If $2^2 = 5$ then I get first class" is logically equivalent to

  1. $2^2 = 5$ and I donot get first class

  2. $2^2 = 5$ or I do not get first class

  3. $2^2 \neq 5$ or I get first class

  4. None of these


Correct Option: C
Explanation:

Obviously, ${ 2 }^{ 2 }\neq 5$, then the statement will be ${ 2 }^{ 2 }\neq 5$ or $I$ get first class.

Logically equivalent statement to $p \leftrightarrow  q$ is

  1. $(p \rightarrow q)\wedge (q \rightarrow p)$

  2. $(p \wedge q)\vee (q \rightarrow p)$

  3. $(p \wedge q)\rightarrow (q \vee p)$

  4. none of these


Correct Option: A
Explanation:
 $p$  $q$  $p\leftrightarrow q$
 T  T  T
 T  F  F
 F  T  F
 F  F  T
 $p$  $q$  $p\rightarrow q$  $q\rightarrow p$ $\left( p\longrightarrow q \right) \wedge \left( q\longrightarrow p \right) $ $p\wedge q$  $\left( p\wedge q \right) \vee \left( q\longrightarrow p \right) $ $q\vee p$  $\left( p\wedge q \right) \longrightarrow \left( q\vee p \right) $ 
 T  T  T  T  T  T  T  T  T
 F  F  T  F  F  T  T  T
 F  T  T  F  F  F  F  T  T
 F  T  T  T  F  T  F  T

Which one of the statement gives the same meaning of statement
If you watch television, then your mind is free and if your mind is free then you watch television

  1. You watch television if and only if your mind is free.

  2. You watch television and your mind is free.

  3. You watch television or your mind is free.

  4. None of these


Correct Option: B
Explanation:
"You watch television and your mind is free".
The above statement gives or suits for the same meaning of the structure given because it is logically correct.

Which of the following is NOT true for any two statements $p$ and $q$?

  1. $\sim[p\vee (\sim q)]=(\sim p)\wedge q$

  2. $\sim(p\vee q)=(\sim p)\vee (\sim q)$

  3. $q\wedge \sim q$ is a contradiction

  4. $\sim (p\wedge (\sim p))$ is a tautology


Correct Option: B
Explanation:
$p$ and $q$ are two statements.
$A) LHS = \sim [pv (\sim q)]$
By De morgon's laws
$\sim(pr (\sim q))= \sim pnq$
$\therefore (A) $ is true .

$B) \sim(p v q) = (\sim p) \vee (\sim q)$
According to demorgon's laws, this is false.
$\because \sim (p \vee q) = (\sim p)\wedge (\sim q)$. 
$\therefore (B)$ is false.

$C) q \wedge \sim  q$ is a contradiction because $'q'$ and $\sim q$ are opposite statements i.e, cannot be there at the same time.

$D) \sim (p \wedge (\sim p))$
$p \wedge (\sim p)$ is a contradiction, which is evident from option $(C)$. $\therefore $ opposite of a contradiction is a tautology .
$\therefore [B]$ is wrong.

If p and q are two statements, then statement $p\Rightarrow q\wedge \sim q$.

  1. Tautology

  2. Contradiction

  3. Neither tautology nor contradiction

  4. None of these


Correct Option: A

The statement $\sim (p \leftrightarrow \sim q)$ is

  1. Equivalent to $\sim p \leftrightarrow q$

  2. A tautology

  3. A fallacy

  4. Equivalent to $p \leftrightarrow q$


Correct Option: C

The proposition $\left( {p \wedge q} \right) \Rightarrow p$ is 

  1. neither tautology nor contradiction

  2. A tautology

  3. A contradiction

  4. Cannot be determined


Correct Option: C

The only statement among the following that is a tautology is-

  1. $A\wedge \left( A\vee B \right) $

  2. $A\vee \left( A\wedge B \right) $

  3. $[A\wedge (A\rightarrow B)]\rightarrow B$

  4. $B\rightarrow [A\wedge (A\vee B)]$


Correct Option: C

A clock is started at noon. By 10 min past 5, the hour hand has turned through

  1. $145^{o}$

  2. $150^{o}$

  3. $155^{o}$

  4. $160^{o}$


Correct Option: C
Explanation:

Angle traced by hour hand in 12 h = $360^{o}$

Angle traced by hour hand in 5 h 10 min i.e., $\dfrac{31}{6} h$ $\implies (\dfrac{360}{12} \times \dfrac{31}{6})^{o}$ = $155^{o}$

A symbol $(\alpha)$ is used to represent 10 flowers. Number of symbols to be drawn to show 60 flowers is

  1. $6\alpha$

  2. $12\alpha$

  3. $20\alpha$

  4. $24\alpha$


Correct Option: A
Explanation:

A symbol α is used to represent 10 flowers.
60 flowers = 6 ×  10 = 6α

Write the converse and contrapositive of the statement
"If it rains then they cancel school."
$(i)$Converse of the statement :
If they cancel school then it rains.
$(ii)$Contrapositive of the statement:
If it does not rain then they do not cancel school.

  1. $(i)$True and $(ii)$False

  2. $(i)$False and $(ii)$True

  3. $(i)$True and $(ii)$True

  4. $(i)$False and $(ii)$False


Correct Option: A
Explanation:

"If it rains then they cancel school."
$(i)$Converse of the statement :
If they cancel school then it rains.
$(ii)$Contrapositive of the statement:
If they do not cancel school then it does not rain.

Write the converse and contrapositive of the statement
"If a dog is barking,then it will not bite"
$(i)$Converse of the statement:If a dog will bite then the dog is barking.
$(ii)$Contrapositive of the statement:If a dog will bite then the dog is not barking.

  1. $(i)$True $(ii)$False

  2. $(i)$True $(ii)$True

  3. $(i)$False $(ii)$False

  4. $(i)$False $(ii)$True


Correct Option: D
Explanation:

"If a dog is barking,then it will not bite"
$(i)$Converse of the statement:If a dog will not bite then the dog is barking.
$(ii)$Contrapositive of the statement:If a dog will bite then the dog is not barking.

Write the dual of the following statement:
(p$\vee$ q)$\wedge$ T

  1. (p$\wedge$ q) $\vee$ T

  2. (p$\wedge$ q) $\vee$ F

  3. (p$\vee$ q) $\vee$ F

  4. (p$\vee$ q) $\vee$ T


Correct Option: B
Explanation:

To obtain the dual of a formula , replace ∧ with V, T with F and vice versa

So, B is correct option.

Which of the following is true about the converse and contrapositive of the statement
"If two triangles are congruent, then their areas are equal."
(i) Converse of the statement :
If the areas of the two triangles are equal, then the triangles are congruent.
(ii) Contrapositive of the statement:
If the areas of the two triangles are not equal, then the triangles are not congruent.

  1. (i) True (ii) False

  2. (i) False (ii) True

  3. (i) True (ii) True

  4. (i) False (ii) False


Correct Option: C
Explanation:

"If two triangles are congruent, then their areas are equal."
(i) Converse of the statement :
If the areas of the two triangles are equal, then the triangles are congruent.
(ii) Contrapositive of the statement:
If the areas of the two triangles are not equal, then the triangles are not congruent.

Identify the Law of Logic: $p \wedge q \equiv q \wedge p$

  1. Idempotent Law

  2. Commutative Law

  3. Associative Law

  4. Conditional Law


Correct Option: B
Explanation:
Given logic 
$p\wedge q\equiv q \wedge p$ 
 It is commutative law 
according to commutative law the order does not matter
we can also check it by truth table 

$p\wedge q$ is logically equivalent to

  1. $\sim(p\rightarrow\sim q)$

  2. $(p\rightarrow\sim q)$

  3. $(\sim p\rightarrow\sim q)$

  4. $(\sim p\rightarrow q)$


Correct Option: A
Explanation:
$p$ $q$ $p\wedge q$ $\sim(p\rightarrow\sim q)$
$T$ $T$ $T$ $T$
$T$ $F$ $T$ $T$
$F$ $F$ $T$ $T$
$F$ $T$ $T$ $T$

$(p\wedge q)\longrightarrow $$\sim(p\rightarrow\sim q)$ is a tautology.

The contrapositive of $p \to \left( { \sim q \to  \sim r} \right)$ is 

  1. $\left( { \sim q \wedge r} \right) \to \sim p$

  2. $\left( {q \wedge \sim r} \right) \to \sim p$

  3. $p \to \left( { \sim r \vee q} \right)$

  4. $p \wedge \left( {q \vee r} \right)$


Correct Option: A
Explanation:

Contraceptive of $a \rightarrow b$ is $\sim b \rightarrow \sim a$


Then

Contraceptive of $p \rightarrow (\sim q \rightarrow \sim r )$

$\equiv \sim (\sim q \rightarrow \sim r) \rightarrow \sim p$

$\equiv \sim (q \wedge \sim r) \rightarrow \sim p [a \rightarrow b \equiv \sim a \wedge b]$

$\equiv (\sim q \vee r) \rightarrow \sim p $  [Demorgas law]

$A$ is correct.

$\sim (p \vee q)$

  1. $p \wedge \sim q$

  2. $p \wedge q$

  3. $\sim p \wedge \sim q$

  4. $\sim p \vee \sim q$


Correct Option: C
Explanation:

$\sim (p\vee q)$

By using De morgan's theorem,
$\sim p\wedge \sim q$

Statement I : if p is false statement and q is true statement, then $ \sim \,p\, \wedge \,q$ is true
Statement II : $ \sim \,p\, \wedge \,q$ is equivalent to $ \sim \left( {pV \sim \,q\,} \right)$

  1. Statement I is true and Statement II is the correct explanation for statement.

  2. Statement I is true and Statement II is true. Statement II is not the correct explanation for the Statement I.

  3. Statement I is true but Statement II is false.

  4. Statement I is false but Statement II is true


Correct Option: A
Explanation:
p q $ \sim p$ $ \sim q$ (i)$ \sim \,p\, \wedge \,q$ $p\,\, \vee \, \sim \,q$ (ii)$ \sim \left( {p\,\, \vee \, \sim \,q} \right)$
T T F F F T F
T F F T F T F
F T T F T F T
F F T T F T F

p is false
q is true
$ \sim p\, \wedge \,q$ is true
from (i) & (ii)
$ \sim p\, \wedge \,q$ = $ \sim \left( {p\,\, \vee  \sim \,\,q} \right)$
Statement (i) & (ii) is correct 
$ \sim \left( {p\,\, \vee  \sim \,\,q} \right)\, = \, \sim \,p\, \wedge \, \sim \,\left( { \sim \,q} \right)$
$ = \, \sim \,p\, \wedge \,\,q$

$ \sim (p \vee q) \vee ( \sim p \wedge q)$ is logically euivalent to 

  1. $ \sim p$

  2. p

  3. q

  4. $ \sim q$


Correct Option: C
Explanation:

${ \sim  }({ p }{ \vee  }{ q }){ \vee  }({ \sim  }{ p }{ \wedge  }{ q })\ ={ \sim  }({ U }){ \vee  }({ q }{ \wedge  }{ q })\ ={ \phi  }{ \vee  }({ q })\ ={ q }$


Where U is universal set , $\phi $ is nulll set and p and q are two disjoint sets 
Correct option is C

Cost of a diamond varies directly as the square of its weight.A diamond broke into four pieces with their weight in the ratio $1:2:3:4$ If the loss in the total value of the diamond was $Rs.\ 70000$. Find the prices of the original diamond.

  1. $10000\ Rs$

  2. $100000\ Rs$

  3. $1000000\ Rs$

  4. $2000000\ Rs$


Correct Option: B
Explanation:

Let, the weights of the four pieces of the diamond $x,2x,3x,4x$ respectively.

$\therefore$ Total weight of the original diamond$=x+2x+3x+4x=10x$
Let, price of the original diamond$=k{ (100{ x }^{ 2 }) },where\quad k\quad is\quad constant$
$\therefore$ Cost of four pieces$=k({ x }^{ 2 }+4{ x }^{ 2 }+9{ x }^{ 2 }+16{ x }^{ 2 })\ =k(30{ x }^{ 2 })$
Loss in the total value of the diamond,
$k(100{ x }^{ 2 })-k(30{ x }^{ 2 })=70000\ \Rightarrow k(70{ x }^{ 2 })=70000\ \Rightarrow k{ x }^{ 2 }=Rs.1000$
Hence, price of the original diamond$=k(100{ x }^{ 2 })\ =1000\times 100=Rs.100000.$

Which of the following is always true ? 

  1. $\left( {p \to q} \right) \cong \left( { \sim q \to \sim p} \right)$

  2. $ \sim \left( {p \vee q} \right) \cong \left( { \sim p \vee \sim q} \right)$

  3. $ \sim \left( {p \to q} \right) \cong \left( {p \vee \sim q} \right)$

  4. $ \sim \left( {p \wedge q} \right) \cong \left( { \sim p \wedge \sim q} \right)$


Correct Option: C
Explanation:

We know that 


$p\rightarrow q\equiv \sim p\wedge q$

$\sim (p\rightarrow q)\equiv \sim (\sim p\wedge q)$

$\sim (p\rightarrow q)\equiv p\vee \sim q$               (De morgan's law)

$C$ is correct

The Boolean expression $ \sim\ ( p \vee q ) \vee ( \sim\ p \wedge q ) $ is equivalent to:

  1. $p$

  2. $q$

  3. $ \sim q $

  4. $ \sim p $


Correct Option: D
Explanation:
$\sim (p\vee q) \vee  (\sim p\wedge q)$
$=(\sim p \wedge \sim q) \vee (\sim p\wedge q)$
$=\sim p\wedge (\sim q\vee q)$
$=\sim p\wedge T$
$=\sim p$

$p \leftrightarrow q \equiv  \sim \left( {p\Delta  \sim q} \right)\Delta  \sim \left( {q\Delta  \sim p} \right)$

  1. True

  2. False


Correct Option: A

Let $p$ and $q$ be two statements, then $ \sim ( \sim p \wedge q) \wedge (p \vee q)$ is logically equivalent to 

  1. $q$

  2. $p\vee q$

  3. $p$

  4. $p\vee \sim q$


Correct Option: D

$ \sim (p \wedge q) \to ( \sim p \vee ( \sim p \vee q))$  is equivalent to 

  1. $p \vee \sim q$

  2. $p \wedge \sim q$

  3. $ \sim p \vee q$

  4. $ \sim p \wedge q$


Correct Option: B

$\left( { \sim p\Delta q} \right)V\left( { \sim p\Delta  \sim q} \right)V\left( { \sim p\Delta  \sim q} \right) \equiv  \sim pV \sim q$

  1. True

  2. False


Correct Option: A

The compound proposition which is always false is:

  1. $\left(p \rightarrow q\right)\leftrightarrow \left( \sim q \rightarrow \sim p \right) $

  2. $\left[ \left( p\rightarrow q \right) \wedge \left( q\rightarrow r \right) \right]\rightarrow \left( p\rightarrow r \right) $

  3. $\left( \sim p\vee q \right) \leftrightarrow \left( p\wedge \sim q \right) $

  4. $p \rightarrow \sim p$


Correct Option: A

$p \wedge ( q \wedge r )$  is logically equivalent to

  1. $p \vee ( q \wedge r )$

  2. $( p \wedge q ) \wedge r$

  3. $( p \vee q ) \vee r$

  4. $p \rightarrow ( q \wedge r )$


Correct Option: B

If  $p$ and  $q$ are two simple proposition then  $p \rightarrow q$  is false when

  1. $p \text { is true and } q \text{ is true}$

  2. $p \text { is false and } q  \text{ is true}$

  3. $p \text { is true and } q \text{ is false}$

  4. both $p$ and $q$ are false


Correct Option: B

Let  $p :$  Mathematics is interesting and let  $q:$  Mathematics is difficult, then the symbol  $p\wedge q$  means

  1. Mathematics is interesting implies that Mathematics is difficult

  2. Mathematics is interesting implies and is implied by Mathematics is difficult

  3. Mathematics is interesting and Mathematics is difficult

  4. Mathematics is interesting or Mathematics is difficult


Correct Option: C
Explanation:

$'\Lambda '$ stands for logical and 

$\therefore$    $p\Lambda q$ means 
Mathematics is interesting and Mathematics is difficult.

The dual of the statement $\left[ p\wedge \left( \sim q \right)  \right] \wedge \left( \sim p \right)] $ is

  1. $p\vee \left( \sim q \right) \vee \sim p$

  2. $\left( p\vee \sim q \right) \vee \sim p$

  3. $p\wedge \sim \left( q\vee \sim p \right) $

  4. none of these


Correct Option: B

The contrapositive of the sentence $\sim p \rightarrow q$ is equivalent to

  1. $p \rightarrow \sim q$

  2. $q \rightarrow \sim p$

  3. $q \rightarrow p$

  4. $\sim p \rightarrow \sim q$

  5. $\sim q \rightarrow \sim p$


Correct Option: E
Explanation:

For a conditional statement p → q, Its converse statement (q → p) and inverse statement (∼p → ∼q) are equivalent to each other. p → q and its contrapositive statement (∼q → ∼p) are equivalent to each other.

Write the inverse and contrapositive of the statement
"If two triangles are congruent, then their areas are equal."
$(a)$Inverse of the statement :
If two triangles are not congruent, then their areas are equal.
$(b)$Contrapositive of the statement:
If the areas of the two triangles are equal, then the triangles are congruent.

  1. $(a)False$ and $(b)$ False

  2. $(a)True$ and $(b)$ False

  3. $(a)False$ and $(b)$ True

  4. $(a)True$ and $(b)$ True


Correct Option: A
Explanation:

"If two triangles are congruent, then their areas are equal."
$(a)$Inverse of the statement :
If two triangles are not congruent, then their areas are not equal.
$(b)$Contrapositive of the statement:
If the areas of the two triangles are not equal, then the triangles are not congruent.

What is the symbolic form and truth value of the following?
"If $4$ is an odd number, then $6$ is divisible by $3$." 
p: $4$ is an odd number.
q: $6$ is divisible by $3$.

  1. p$\rightarrow$q and $F$

  2. q$\rightarrow$p and $T$

  3. q$\rightarrow$p and $F$

  4. p$\rightarrow$q and $T$


Correct Option: D
Explanation:

$p: 4$ is an odd number.
$q: 6$ is divisible by $3$.
Symbolic form: $p$ $\rightarrow$ $q$
$p$ is false and $q$ is true.
So, $F\rightarrow T$ is $T$.

Identify the Law of Logic
$\sim(\sim p) \equiv p$

  1. DeMorgan's Law

  2. Conditional Law

  3. Involution Law

  4. Complement Law


Correct Option: C
Explanation:

Involution Law

This law states that if you negate a negation they effectively cancel each other out.
$\sim (\sim p)\equiv p$

Which of following is the negation of $(P \ \vee\sim Q).$

  1. $\sim P\vee Q$

  2. $\sim P\wedge Q$

  3. $\sim Q\wedge P$

  4. $\sim Q\vee P$


Correct Option: B
Explanation:
 P  Q  $\sim P$  $\sim Q$  $P\vee \sim Q$ $\sim \left( P\vee \sim Q \right) $  $\sim P\wedge Q$ 
 T  F  F  T  F  F
T  F  T  T  F  F
F  T  F  F  T  T
F F  T  T  F  T  F
Therefore, $\sim \left( P\vee \sim Q \right) $ is $\sim P\wedge Q$ 

Identify the Law of Logic
$p \wedge T \equiv T$
$p \vee F \equiv F$

  1. Complement Law

  2. Identity Law

  3. Involution Law

  4. Absorption Law


Correct Option: B
Explanation:

Identity Law

Identity law observes how certain expression will behave when one of the terms is fixed
$p \vee F \equiv F$ and $p\wedge T\equiv T$

Is $(p\rightarrow q)\vee (q\rightarrow p)$  a tautology ?

  1. True

  2. False


Correct Option: A
Explanation:
$p$ $q$ $(p\rightarrow q)$ $(q\rightarrow p)$ $(p\rightarrow q)\vee(q\rightarrow p)$
T T             T              T                               T
T F             F              T                               T
F T             T              F                               T
F F             T              T                               T               

The given statement is a tautology as the truth table has all the values as true in the output which is the property of tautology

Identify the Law of Logic
$(p \vee q) \vee r \equiv p \vee (q \vee r) \equiv p \vee q \vee r$

  1. Associative law

  2. Commutative Law

  3. Involution Law

  4. Conditional Law


Correct Option: A
Explanation:

Associative Law

This law allows the removal of brackets from an expression and regrouping of the variables.
$(p\vee q)\vee r \equiv p \vee (q \vee r)\equiv p\vee q\vee r$

Identify the Law of Logic
$\sim(p \wedge q) \equiv \sim p \vee \sim q$

  1. Commutative Law

  2. DeMorgan's Law

  3. Complement Law

  4. Conditional Law


Correct Option: B
Explanation:
Given 
$\sim (p\wedge q)=\sim p \vee \sim q$

It is Demorgan's law 
according to the if we take transpose or negation of any quatity then all the relation get opposite

The equivalent statement of $(p \vee q) \wedge \sim p$ is?

  1. $\sim p \vee q$

  2. $ p \wedge \sim q$

  3. $\sim p \wedge q$

  4. $ p \vee q$


Correct Option: C
Explanation:

$(p\vee q)\wedge \sim p$
$=(p\wedge \sim p)\vee (q\wedge \sim p)$ Distributive Law
$=F\vee (q\wedge \sim p)$ Negation Law
$=(q\wedge \sim p)$ Identity Law
$=(\sim p \wedge q)$ Commutative Law

$p\rightarrow q$ is equivalent to

  1. $\sim p\vee \sim q$

  2. $ p\vee \sim q$

  3. $\sim p\vee q$

  4. $\sim p\wedge q$


Correct Option: C
Explanation:
$p$ $q$ $p\rightarrow q$ $\sim p\vee q$
$T$ $T$ $T$ $T$
$T$ $F$ $T$ $T$
$F$ $F$ $T$ $T$
$F$ $T$ $T$ $T$

$(p\rightarrow q)\longleftrightarrow (\sim p\vee q)$ is a tautology.

The statement $(p \wedge q) \vee (\sim p \wedge \sim q) $ is equivalent to?

  1. $p \leftrightarrow q$

  2. $p \rightarrow q$

  3. $p \leftrightarrow \sim q$

  4. $\sim p \rightarrow q$


Correct Option: A
Explanation:
given statement 
$(p\wedge q)\vee (\sim p\wedge \sim q)$
$(p\wedge q)\vee (\sim p\wedge \sim q)$
$(p\wedge q)\vee (\sim(p\wedge  q))$
$(p\wedge q)\wedge(p\wedge  q)$
$p\leftrightarrow q$

$p \leftrightarrow q \equiv ?$

  1. $\sim (p \vee \sim q) \wedge \sim(p \wedge \sim q)$

  2. $\sim (p \wedge \sim q) \wedge \sim(p \wedge \sim q)$

  3. $\sim (p \wedge \sim q) \wedge \sim(p \vee \sim q)$

  4. None of these


Correct Option: D
Explanation:

$p\leftrightarrow q=(p\rightarrow q)\wedge (q \rightarrow p)$
We know that $(p\rightarrow q)=(\sim p \vee q)$
So,
$(p\rightarrow q)\wedge (q \rightarrow p)=(\sim p \vee q)\wedge (\sim q \vee p)$
Now, apply the De'morgan law state that $\sim(p\vee q)= (\sim p \wedge \sim q)$
Therefore,
$(\sim p \vee q)\wedge (\sim q \vee p)=\sim (p \wedge \sim q) \wedge \sim (q\wedge \sim p) $

Identify the Law of Logic
$\sim(p \vee q) \equiv \sim p \wedge \sim q$

  1. Conditional Law

  2. Demorgan's Law

  3. Absorption Law

  4. Identity Law


Correct Option: B
Explanation:
Given 
$\sim (p\wedge q)=\sim p \vee \sim q$

It is Demorgan's law 
according to the if we take transpose or negation of any quatity then all the relation get opposite

Identify the Law of Logic
$p \rightarrow q \equiv \sim p \vee q$

  1. Idempotent Law

  2. Conditional Law

  3. Involution Law

  4. Commutative Law


Correct Option: B
Explanation:
|  $p$ |  $q$ |  $p\rightarrow q$ |  $\sim p$ |  $(\sim p)\vee q$ | | --- | --- | --- | --- | --- | |  $T$ |   $T$ |   $T$ |   $F$ |   $T$ | |   $T$ |   $F$ |   $F$ |   $F$ |   $F$ | |  $F$ |   $T$ |   $T$ |   $T$ |   $T$ | |   $F$ |   $F$ |   $T$ |   $T$ |   $T$ |
We can say that if $p$ ,then $q$ or $p$ implies $q$ .
'$\rightarrow$' is called a conditional operator.
So, the giving logical equivalence is the conditional law.

Let p and q be any two logical statements and $r : p \rightarrow (\sim p \vee q)$. If r has a truth value F, then the truth values of p and q are respectively

  1. F, F

  2. T, T

  3. F, T

  4. T, F


Correct Option: D
Explanation:
p q $\sim$p $\sim$ p $\vee$ q r
T T F T T
F F T T T
T F F F F
F T T T T

$\therefore$ Clearly from above able, If r has a truth value F, then the truth values of p and core T and F respectively.

State, whether the is given the statement, is True or False.
$\sim [(p \vee \sim q) \rightarrow (p \wedge \sim q)] \equiv (p \vee \sim q) \wedge (\sim \vee q)$

  1. True

  2. False


Correct Option: A
Explanation:
 $p$  $q$  $\sim q$  $(p\vee \sim q)$  $(p\wedge \sim q)$ $(p\vee \sim q)\rightarrow (p\wedge \sim q)$  $\sim[(p\vee \sim q)\rightarrow (p\wedge \sim q)]$
 $T$  $T$  $F$  $T$  $F$  $F$  $T$
 $T$  $F$  $T$  $T$  $T$  $T$   $F$
 $F$  $T$  $F$  $F$  $F$  $T$   $F$
 $F$  $F$  $T$  $T$  $F$  $F$ $T$
 $p$  $q$  $\sim q$  $(p\vee \sim q)$ $\sim p$  $(\sim p \vee q)$ $(p\vee \sim q)\wedge (\sim p \vee q)$
 $T$  $T$  $F$  $T$  $F$  $T$  $T$
 $T$  $F$  $T$  $T$  $F$  $F$  $F$
 $F$  $T$  $F$   $F$  $T$  $T$  $F$
 $F$  $F$  $T$  $T$  $T$  $T$  $T$

$\sim (p \vee q) \vee (\sim p \wedge q) \equiv ?$

  1. $\sim q$

  2. $q$

  3. $\sim p$

  4. $p$


Correct Option: C
Explanation:

$\sim (p\vee q)\vee (\sim p \wedge q)$
$=(\sim p \wedge \sim q) \vee (\sim p \wedge q)$ De'Morgan Law
$=(\sim p)\wedge (\sim q\vee q)$ Distributive Law
$=(\sim p)\wedge T$ Negation Law
$=\sim p$ Identity law

State whether the following statements is True or False?
$p \leftrightarrow q \equiv (p \wedge q) \vee (\sim p \wedge \sim q)$

  1. True

  2. False


Correct Option: A
Explanation:
given statement 
$p\leftrightarrow q=(p\wedge q)\vee (\sim p\wedge \sim q)$
taking RHS
$(p\wedge q)\vee (\sim p\wedge \sim q)$
$(p\wedge q)\vee (\sim(p\wedge  q))$
$(p\wedge q)\wedge(p\wedge  q)$
$p\leftrightarrow q$
It is true

Let p,q be statements. Negation of statement $p \leftrightarrow  ~ q$, is

  1. $~ q \rightarrow p$

  2. $ ~ p v q$

  3. $p \leftrightarrow q$

  4. $p \rightarrow q$


Correct Option: A
Explanation:
p q ~q $p \leftrightarrow ~q$ $~(p \leftrightarrow ~q)$ $~q \rightarrow p$ $~p v q$ $p \leftrightarrow q$ $p \rightarrow q$
T T F F T T T T T
T F T T F T F F F
F T T T F T T F T
F F F F T F T T T
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