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Rational Numbers

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What is the value of the following expression?

{- 4/3 x 5/4 x - 3/5 x 6/7 x (14/12 x 13/11 x 33/39) } / 2

  1. 2

    • 2
    • 1/2
  2. 1/2

  3. 1


Correct Option: D
Explanation:

{- 4/3 x 5/4 x - 3/5 x 6/7 x (14/12 x 13/11 x 33/39) } / 2

= {- 4/3 x 5/4 x - 3/5 x 6/7 x 14/12 x 13/11 x 33/39} / 2

= {1 x 6/7 x 7/6 x 13/11 x 11/13} / 2

= {1}/2

= 1/2

Which number should be subtracted from reciprocal of 12 so that we can get a number, which is reciprocal of 10?

  1. 60

    • 60
    • 1/60
  2. 1/60

  3. 22


Correct Option: C
Explanation:

Let the number be X.    1/12 - X = 1/10    1/12 - 1/10 = X   (5 - 6) / 60 = X

  • 1/60    = X 

Therefore, the number to be subtracted is - 1/ 60.

Which of the following statements is correct?

  1. Addition is associative.

  2. Subtraction is not associative.

  3. Multiplication is associative.

  4. All of these

  5. None of these


Correct Option: D
Explanation:

Option (1) is true, as for any three integers a,b and c, a + (b + c) = (a + b) + c Therefore, addition is associative. Option (2) is true as 5 - (8 - 3) is not equal to ( 5 - 8) - 3. Or 5 - 5 is not equal to - 3 - 3. Option (3) is true, as for three integers a, b and c, a  x ( b x c ) = ( a x b ) x c Therefore, all the three options are correct. 

Which of the following rational numbers lies between 2/3 and 4/5?

    • 7/10
  1. 16/20

  2. 3/4

    • 3/4
  3. 3/10


Correct Option: C
Explanation:

Value of 2/3 = 0.66 Value of 4/5 = 0.8 Value of - 7/10 = - 0.7 Value of 16/20 = 0.8 Value of 3/4 = 0.75 Valvue of - 3/4 = - 0.75 Value of 3/10 = 0.3 Therefore, 3/4 lies between the given two rational numbers.

Which of the following statements is/are correct?

  1. Additive inverse of - 121/10 is greater than 10.

  2. Multiplicative inverse of 10/18 is less than 1.

  3. Sum of number and its additive inverse is 0.

  4. Product of a number and its multiplicative inverse is - 1.

  5. Both (1) and (3)


Correct Option: E
Explanation:

Statement (1) is correct, as additive inverse of - 121/10 is 121/10, which is greater than 10. Statement (2) is incorrect, as multiplicative inverse of 10/18 is 18/10, which is more than 1. Statement (3) is correct, as sum of a number and its additive inverse is 0. Statement (4) is incorrect, as product of a number and its multiplicative inverse is 1. Therefore, both (1) and (3) are correct.

Which of the following rational numbers is less than - 17771/ 23333?

    • 17770/ 23333
  1. 17771/23333

    • 17769/ 23333
    • 17771/ 5000
    • 17772/ 23333

Correct Option: E
Explanation:

Correct, as this option is less than the given number.

  • 17771/ 23333 > - 17772/ 23333

If you add 1/4 to a number and multiply the result by (4/8 - 8/16 + 1/2 + 1/3), you get 1/10. What is the number?

  1. 13/100

    • 13/100
    • 100/13
  2. 100/13

    • 131/100

Correct Option: B
Explanation:

Let the number be X. (X + ¼ ) (4/8 - 8/16 + ½ + 1/3) = 1/10  (X + ¼ ) (1/2 - 1/2 + ½ + 1/3) = 1/10 (X + ¼ ) ( ½ + 1/3) = 1/10 (X + ¼ ) (5/6) = 1/10 X + ¼ = 6/50 X = 6/50 - ¼ X = (12 - 25)/100 X = - 13/100

Find the sum of additive inverse and multiplicative inverse of the following expression? (abc/de)

  1. {(de)2 + (abc)2}/ abcde

  2. {(de)2 - (abc)2}/ abcde

  3. {(de)2 - (abc)2}/ abde

  4. {(de)2 - (abc)2}/ de

  5. {(de)2 - (abc)2}/ abc


Correct Option: B
Explanation:

Given expression is (abc/de). Additive inverse of the given expression is (- abc/de). Thus, abc/de - abc/de = 0 Multiplicative inverse of the given expression is (de/abc). Thus, abc/de x de/abc = 1 So, the required sum of additive inverse and multiplicative inverse = - abc/de + de/abc = {(de)2 - (abc)2}/ abcde

Which of the following statements is/are correct?

  1. There are 10 rational numbers between 1/20 and 11/20.

  2. There are 30 rational numbers between 1/41 and 31/41.

  3. There are 11 whole numbers between 20 and 32.

  4. There are infinite rational numbers between - 1/34 and 1/34.

  5. Both (3) and (4)


Correct Option: E
Explanation:

Option (1) is incorrect, as there are infinite rational numbers between 1/20 and 11/20. Option (2) is incorrect, as there are infinite rational numbers between 1/41 and 31/41. Option (3) is correct, as there are 11 whole numbers between 20 and 32, i.e. 21 to 31. Option (4) is correct, as there can be infinite rational numbers between any two rational numbers. Hence, 5th option is the answer.

Which of the following statements is/are true for the numbers from - 5 to 10?

  1. There are 15 natural numbers in the given range of numbers.

  2. There are 10 whole numbers in the given range of numbers.

  3. There are 11 whole numbers in the given range of numbers.

  4. There are infinite rational numbers in the given range of numbers.

  5. Both (3) and (4)


Correct Option: E
Explanation:

Statement (1) is incorrect, as there are only 10 natural numbers in the range from 1 to 10. Statement (2) is incorrect, as there are 11 whole numbers in the given range of numbers. Statement (3) is correct, as there are 11 whole numbers in the range from 0 to 10. Statement (4) is correct, as there can be infinite rational numbers in between any 2 or more integers or rational numbers. Hence, both (3) and (4) options are correct.

Find the value of the following expression.

{( 25/36 x 216/125) + (2401/343 x 1296/216) } / {(- 25/36 x 6/5) + (- 4/9 x 81/64)}.

  1. 216/5 x 48/67

    • 216/5 x 48/67
  2. 5/216 x 67/48

  3. 67/48 x 5/216

    • 5/216

Correct Option: B
Explanation:

The given expression is {( 25/36 x 216/125) + (2401/343  x 1296/216) } / {(- 25/36 x 6/5) + (- 4/9 x 81/64)} Solve the expression part by part: ( 25/36 x 216/125) = 25/36 x 216/125 = 6/5

(2401/343 x 1296/216) = 7 x 6 = 42

  • 25/36 x 6/5 = - 5/6
  • 4/9 x 81/64 = - 9/16 Therefore, the required value of the expression is    6/5 + 42 / - 5/6 - 9/16  = {(216/5) / {(- 40 - 27)/48} = - 216/5 x 48/67

What is the additive inverse of (3/7) + (- 6/11) + (- 16/42) + (10/44)?

    • 125/462
    • 12/22
  1. 30/132

  2. 125/462

  3. 250/462


Correct Option: D
Explanation:

(3/7) + (- 6/11) + (- 16/42) + (10/44) For finding the additive inverse of the above expression, we need to find the value of the above expression. Additive inverse of a number is negative value of the same number. So, addition of these two numbers will be zero. For example, additive inverse of 1 is - 1. Now, the value of the given expression: 3/7 - 6/11 - 16/42 + 10/42 = 3/7 - 6/11 - 8/21 + 5/22 = 198/462 - 252/462 - 176/462 + 105/462 = (198 - 252 - 176 + 105) / 462 = - 125/462

Therefore, additive inverse of the given expression is (125/462) so that 125/ 462 - 125/462 = 0.

What is the additive inverse of the following expression?

(1/2 + 1/3 + ¼ ) / (½ - 1/3)

    • 13/2
  1. 13/2

  2. 1/6

  3. 13/12


Correct Option: A
Explanation:

(1/2 + 1/3 + ¼ ) / (½ - 1/3) For finding the additive inverse of the above expression, we need to find the value of the above expression.

Additive inverse of a number is negative value of the same number. So, addition of these two numbers will be zero. For example, additive inverse of 1 is - 1 (As 1 - 1 = 0).

Now, the value of the given expression is (1/2 + 1/3 + ¼ ) / ( ½ - 1/3)

= {(6 + 4 + 3) / 12} / {( 3-2)/6}

= {13/12} / {1/6}

= 13/2

Therefore, additive inverse of the given expression is - 13/2 so that 13/2 - 13/2 = 0.

What is multiplicative inverse of the following expression?

{ ½ - 2/4 + 1/3 - ¼ } / {½ - 2/4 + 1/3 + ¼ } ?

    • 1/7
  1. 7

  2. 1/7

  3. 49


Correct Option: B
Explanation:

Multiplicative inverse of a number is equal to the reciprocal of the given number such that product of the given number and its reciprocal is equal to 1. The given expression is { ½ - 2/4 + 1/3 - ¼ } / { ½ - 2/4 + 1/3 + ¼ } = { ½ - ½ + 1/3 - ¼ } / { ½ - ½ + 1/3 + ¼ } = { 1/3 - ¼ } / {1/3 + ¼ } = {1/12} / {7/12} = 1/7

Therefore, multiplicative inverse of the given number is 7.

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