TRB BT Assistant - Probability Distributions and Hypothesis Testing Question Bank with Options

1. The Chi-Squared goodness-of-fit test is used to determine if a sample distribution matches a:

A) Particular theoretical distribution

B) Specific population mean

C) Specific population variance

D) Sample standard deviation

2. When comparing the means of three or more independent groups, which statistical test is most appropriate?

A) Independent samples t-test

B) Paired t-test

C) One-way ANOVA

D) Chi-Squared test for independence

3. What is the fundamental principle behind hypothesis testing?

A) To prove the null hypothesis is true

B) To disprove the null hypothesis or find insufficient evidence to reject it

C) To find the exact population parameter

D) To always accept the alternative hypothesis

4. Which distribution is characterized by skewness and is often used for modeling waiting times?

A) Normal Distribution

B) Binomial Distribution

C) Exponential Distribution

D) Uniform Distribution

5. A p-value of 0.01 is obtained in a hypothesis test with α = 0.05. What is the conclusion?

A) Fail to reject H₀

B) Reject H₀

C) Accept H₀

D) The result is inconclusive

6. What test is used to determine if there is a statistically significant difference between the means of two related groups (e.g., before and after treatment on the same subjects)?

A) Independent samples t-test

B) Paired t-test

C) One-way ANOVA

D) Z-test

7. What test is used to determine if there is a statistically significant difference between the means of two independent groups?

A) Paired t-test

B) One-way ANOVA

C) Independent samples t-test

D) Chi-Squared test

8. In hypothesis testing, if the sample size increases, what generally happens to the width of the confidence interval (assuming other factors remain constant)?

A) It increases

B) It decreases

C) It remains the same

D) It depends on the p-value

9. What is the relationship between the variance and the mean in a Poisson distribution?

A) Variance is twice the mean

B) Variance is half the mean

C) Variance is equal to the mean

D) There is no direct relationship

10. The exponential distribution has a single parameter, usually denoted by λ, which represents:

A) The mean of the distribution

B) The rate parameter

C) The probability of success

D) The number of trials

11. Which of the following distributions is characterized by two parameters: mean (μ) and standard deviation (σ)?

A) Binomial Distribution

B) Poisson Distribution

C) Normal Distribution

D) Exponential Distribution

12. A 95% confidence interval means that:

A) There is a 95% probability that the population parameter falls within the interval

B) If we were to take many samples and construct intervals, 95% of them would contain the true population parameter

C) 95% of the sample data falls within the interval

D) The null hypothesis is true with 95% confidence

13. What is the primary purpose of a confidence interval?

A) To test a specific hypothesis about a population parameter

B) To provide a range of plausible values for a population parameter

C) To determine the probability of observing sample data

D) To calculate the effect size of an experiment

14. The distribution of the sample variance from a normally distributed population follows which distribution?

A) t-distribution

B) F-distribution

C) Chi-Squared distribution

D) Binomial distribution

15. Which of the following is NOT a condition for using the Z-test for a single proportion?

A) The sample is random

B) The population is normally distributed

C) The population size is large enough (np ≥ 10 and n(1-p) ≥ 10)

D) The observations are independent

16. What type of test is appropriate for comparing a sample proportion to a hypothesized population proportion?

A) t-test

B) Z-test for proportions

C) Chi-Squared test

D) F-test

17. In hypothesis testing, a critical region is:

A) The range of values for which we fail to reject the null hypothesis

B) The range of values for which we reject the null hypothesis

C) The probability of committing a Type II error

D) The probability of committing a Type I error

18. The standard normal distribution has a standard deviation of:

A) 0

B) 1

C) 0.5

D) Cannot be determined

19. The standard normal distribution has a mean of:

A) 0

B) 1

C) 0.5

D) Cannot be determined

20. Which probability distribution is often used to approximate the binomial distribution when 'n' is large and 'p' is small?

A) Normal Distribution

B) Poisson Distribution

C) Exponential Distribution

D) Gamma Distribution

21. What does the term 'degrees of freedom' generally refer to in statistical distributions?

A) The total number of observations in a sample

B) The number of independent pieces of information used to estimate a parameter

C) The number of possible outcomes in an experiment

D) The level of significance chosen for a test

22. When conducting a one-sample t-test, what is the null hypothesis typically stating?

A) The sample mean is greater than a hypothesized value

B) The sample mean is less than a hypothesized value

C) The population mean is equal to a hypothesized value

D) The population mean is not equal to a hypothesized value

23. What is the primary assumption for using the standard t-test for independent samples?

A) The two populations have equal variances

B) The two populations have unequal variances

C) The sample sizes are equal

D) The population standard deviations are known

24. In ANOVA (Analysis of Variance), the F-statistic is the ratio of:

A) Mean Square Error to Mean Square Regression

B) Mean Square Treatment to Mean Square Error

C) Sum of Squares Error to Sum of Squares Treatment

D) Mean Square Regression to Mean Square Error

25. The F-distribution is used for comparing:

A) A single population mean to a hypothesized value

B) Two population variances

C) A single population proportion to a hypothesized value

D) The means of more than two populations

26. What are the degrees of freedom for a Chi-Squared test of independence with 'r' rows and 'c' columns?

A) (r-1)(c-1)

B) rc - 1

C) r + c - 1

D) r - 1

27. The Chi-Squared (χ²) distribution is primarily used for testing hypotheses about:

A) Means of two populations

B) Variances of populations

C) Goodness-of-fit and independence of categorical variables

D) Proportions of a single population

28. What is the primary difference between a Z-test and a t-test when comparing two population means?

A) Z-test assumes unequal population variances, t-test assumes equal

B) Z-test is used when population standard deviations are known or sample sizes are large, t-test is used when they are unknown and sample sizes are small

C) Z-test is for categorical data, t-test is for continuous data

D) Z-test is always more powerful than a t-test

29. Which theorem states that the sampling distribution of the sample mean will approach a normal distribution as the sample size gets larger, regardless of the population distribution?

A) Bayes' Theorem

B) Central Limit Theorem

C) Law of Large Numbers

D) Chebyshev's Inequality

30. In the context of normal distribution, what is the standard deviation of the sampling distribution of the sample mean called?

A) Standard error

B) Population standard deviation

C) Sample standard deviation

D) Variance

31. A two-tailed hypothesis test is used when the alternative hypothesis states that a parameter is:

A) Greater than a value

B) Less than a value

C) Equal to a value

D) Not equal to a value

32. The t-distribution is similar to the normal distribution but has heavier tails and is used when:

A) Population variance is known and sample size is large

B) Population variance is unknown and sample size is small

C) Population mean is unknown and sample size is large

D) Population standard deviation is known

33. Which distribution is commonly used for hypothesis testing about the variance of a normally distributed population?

A) t-distribution

B) F-distribution

C) Chi-Squared distribution

D) Z-distribution

34. The power of a statistical test is defined as the probability of:

A) Making a Type I error

B) Making a Type II error

C) Correctly rejecting a false null hypothesis

D) Incorrectly rejecting a true null hypothesis

35. A Type II error occurs when:

A) The null hypothesis is incorrectly rejected when it is true

B) The null hypothesis is incorrectly accepted when it is false

C) The null hypothesis is correctly rejected when it is false

D) The null hypothesis is correctly accepted when it is true

36. What is the probability of committing a Type I error called?

A) Beta (β)

B) Power of the test

C) Significance level (α)

D) Confidence level

37. A Type I error in hypothesis testing occurs when:

A) The null hypothesis is incorrectly accepted when it is false

B) The null hypothesis is incorrectly rejected when it is true

C) The null hypothesis is correctly rejected when it is false

D) The null hypothesis is correctly accepted when it is true

38. If the p-value is less than the significance level (α), what action is typically taken regarding the null hypothesis?

A) Fail to reject the null hypothesis

B) Reject the null hypothesis

C) Accept the null hypothesis

D) Conclude there is insufficient evidence

39. What does a p-value represent in hypothesis testing?

A) The probability of the null hypothesis being true

B) The probability of observing the sample data (or more extreme) if the null hypothesis is true

C) The significance level of the test

D) The effect size of the observed difference

40. The alternative hypothesis (H₁) is a statement that contradicts the:

A) Sample data

B) Alternative hypothesis

C) Null hypothesis

D) P-value

41. In hypothesis testing, what is the null hypothesis (H₀) typically stated as?

A) A statement of no effect or no difference

B) A statement of a significant effect or difference

C) A statement about sample statistics

D) A statement of maximum possible value

42. What is the primary purpose of hypothesis testing in statistics?

A) To describe a population parameter

B) To estimate population parameters

C) To make decisions about population claims based on sample data

D) To calculate the probability of specific outcomes

43. The sum of probabilities for all possible outcomes in any probability distribution must equal:

A) 0

B) 1

C) The mean

D) The variance

44. Which distribution is used for modeling the time until an event occurs in a Poisson process?

A) Normal Distribution

B) Binomial Distribution

C) Chi-Squared Distribution

D) Exponential Distribution

45. What is the parameter 'λ' (lambda) in a Poisson distribution?

A) The number of trials

B) The probability of success

C) The average rate of events

D) The variance of the distribution

46. The Poisson distribution is often used to model the number of events occurring within a fixed interval of what?

A) Space or volume

B) Time or space

C) Probability or frequency

D) Sample size or significance level

47. In a binomial distribution, what does 'n' typically represent?

A) The probability of success on a single trial

B) The number of trials

C) The number of successes

D) The mean of the distribution

48. Which type of probability distribution is characterized by a bell-shaped curve and is symmetric around its mean?

A) Binomial Distribution

B) Poisson Distribution

C) Normal Distribution

D) Exponential Distribution

Probability Distributions and Hypothesis Testing - Question Bank