Final Exam for Probability and Statistics

Which of the following refers to the subset of a population?

• statistic

• variable

• parameter

• sample

Which of the following is a sampling method in which the population is first divided into strata and then samples are randomly selected from each stratum?

• simple random sampling

• stratified sampling

• systematic sampling

• cluster sampling

Which of the following states that the sampling distribution of the sample means approaches a normal distribution as the sample size gets larger?

• Central Limit Theorem

• Law of Large Numbers

• Limit Theorem

• Bayes Theorem

How large is the minimum sample size needed of a certain population in order to obtain a close

approximation of a normal distribution?

• 15

• 20

• 30

• 60

Which of the following is the value of t_(0.05) with a sample size of 10?

• 1.812

• 1.900

• 1.860

• 1.833

Which of the following is the value of t_(0.01) with 11 degrees of freedom?

• 2.764

• 2.681

• 2.821

• 2.718

What is the 99.5th percentile in a t-distribution with 9 degrees of freedom?

• 2.821

• 3.250

• 2.821

• 2.764

If the computed z-value is 2.015 and the critical value is 1.833, which of the following statements could be true?

• It lies in the rejection region, 𝐻𝑜 must be rejected.

• It lies in the rejection region, we failed to reject 𝐻𝑜.

• It lies in the non-rejection region, 𝐻𝑜 must be rejected.

• It lies in the non-rejection region, we failed to reject 𝐻𝑜.

Which of the following must be used as the level of significance if we want a higher possibility of

decision?

• 1%

• 5%

• 10%

• 25%

A one sample t-test is conducted on Ho: μ = 81.6. The sample has a mean of 84.1, s = 3.1, n = 25,and α = .01. What conclusion can be drawn?

• Reject Ho.

• Reject Ha.

• Fail to reject Ho.

• Fail to reject Ha