Probability and Statistics

Description: This quiz covers fundamental concepts and techniques in Probability and Statistics.
Number of Questions: 15
Created by:
Tags: probability statistics random variables distributions hypothesis testing
Attempted 0/15 Correct 0 Score 0

What is the probability of getting a head when flipping a fair coin?

  1. 1/2

  2. 1/3

  3. 1/4

  4. 1/5


Correct Option: A
Explanation:

For a fair coin, the probability of getting a head or a tail is equal, hence the probability of getting a head is 1/2.

In a normal distribution, what is the area under the curve between the mean and one standard deviation?

  1. 0.3413

  2. 0.6826

  3. 0.9545

  4. 0.9973


Correct Option: A
Explanation:

In a normal distribution, the area under the curve between the mean and one standard deviation is approximately 0.3413.

What is the expected value of a random variable X with probability mass function P(X = x) = 1/3 for x = 1, 2, and 3?

  1. 1

  2. 2

  3. 3

  4. 4


Correct Option: B
Explanation:

The expected value of a random variable is calculated as E(X) = ΣxP(X = x). In this case, E(X) = 1(1/3) + 2(1/3) + 3(1/3) = 2.

Which of the following is a discrete probability distribution?

  1. Normal distribution

  2. Binomial distribution

  3. Poisson distribution

  4. Uniform distribution


Correct Option: B
Explanation:

The binomial distribution is a discrete probability distribution that describes the number of successes in a sequence of n independent yes/no experiments, each of which yields success with probability p.

What is the probability of getting at least one head when flipping two fair coins?

  1. 1/4

  2. 1/2

  3. 3/4

  4. 1


Correct Option: C
Explanation:

The probability of getting at least one head is the complement of the probability of getting no heads. The probability of getting no heads is (1/2) * (1/2) = 1/4. Therefore, the probability of getting at least one head is 1 - 1/4 = 3/4.

What is the central limit theorem?

  1. A theorem that states that the sample mean of a large number of independent, identically distributed random variables will be approximately normally distributed.

  2. A theorem that states that the sample variance of a large number of independent, identically distributed random variables will be approximately normally distributed.

  3. A theorem that states that the sample median of a large number of independent, identically distributed random variables will be approximately normally distributed.

  4. A theorem that states that the sample mode of a large number of independent, identically distributed random variables will be approximately normally distributed.


Correct Option: A
Explanation:

The central limit theorem states that the sample mean of a large number of independent, identically distributed random variables will be approximately normally distributed, regardless of the shape of the underlying distribution.

What is the probability of getting a sum of 7 when rolling two fair six-sided dice?

  1. 1/6

  2. 1/12

  3. 1/18

  4. 1/36


Correct Option: A
Explanation:

There are 36 possible outcomes when rolling two dice. The outcomes that sum to 7 are (1, 6), (2, 5), (3, 4), (4, 3), (5, 2), and (6, 1). Therefore, the probability of getting a sum of 7 is 6/36 = 1/6.

What is the probability of getting a king when drawing a card from a standard deck of 52 cards?

  1. 1/13

  2. 4/13

  3. 1/4

  4. 1/52


Correct Option: B
Explanation:

There are 4 kings in a standard deck of 52 cards. Therefore, the probability of getting a king is 4/52 = 1/13.

What is the probability of getting a type A blood group in a population where the frequency of type A blood is 0.4?

  1. 0.4

  2. 0.6

  3. 0.8

  4. 1


Correct Option: A
Explanation:

The probability of getting a type A blood group is equal to the frequency of type A blood in the population, which is 0.4.

What is the probability of getting a z-score between -1 and 1 in a standard normal distribution?

  1. 0.3413

  2. 0.6826

  3. 0.9545

  4. 0.9973


Correct Option: B
Explanation:

The probability of getting a z-score between -1 and 1 in a standard normal distribution is approximately 0.6826.

What is the probability of getting a sample mean between 100 and 110 from a population with a mean of 105 and a standard deviation of 10, if a sample of size 25 is taken?

  1. 0.3413

  2. 0.6826

  3. 0.9545

  4. 0.9973


Correct Option: B
Explanation:

Using the central limit theorem, the probability of getting a sample mean between 100 and 110 can be approximated by the probability of getting a z-score between (100 - 105) / (10 / √25) = -1 and (110 - 105) / (10 / √25) = 1 in a standard normal distribution. This probability is approximately 0.6826.

What is the probability of rejecting a null hypothesis when it is true, also known as a Type I error?

  1. 0.01

  2. 0.05

  3. 0.1

  4. 0.2


Correct Option: B
Explanation:

In hypothesis testing, the probability of rejecting a null hypothesis when it is true is typically set at 0.05, which is known as the significance level.

What is the probability of failing to reject a null hypothesis when it is false, also known as a Type II error?

  1. 0.01

  2. 0.05

  3. 0.1

  4. 0.2


Correct Option: D
Explanation:

In hypothesis testing, the probability of failing to reject a null hypothesis when it is false is known as the Type II error. The probability of a Type II error depends on the significance level, the effect size, and the sample size.

What is the chi-square test used for?

  1. Testing the goodness of fit of a distribution.

  2. Testing the independence of two categorical variables.

  3. Testing the equality of means of two populations.

  4. Testing the equality of variances of two populations.


Correct Option: A
Explanation:

The chi-square test is commonly used for testing the goodness of fit of a distribution, which assesses how well a sample fits a particular distribution.

What is the t-test used for?

  1. Testing the equality of means of two populations.

  2. Testing the equality of variances of two populations.

  3. Testing the independence of two categorical variables.

  4. Testing the goodness of fit of a distribution.


Correct Option: A
Explanation:

The t-test is commonly used for testing the equality of means of two populations, assuming that the populations are normally distributed and have equal variances.

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