I. Multiple-choice questions.

(1) The critical value for a 99.7% confidence interval for the population proportion p is

(A) 1.96 (B) 2 (C) 2.75 (D) 2.96 3

(2) If the 90% confidence interval of the mean of a population is given by 45 3.25, which of the following is correct?

(A) There is a 90% probability that the population mean is in the interval. (B) There is a 90% probability that the sample mean x is in the interval. (C) If 1000 samples of the same size are taken from the population, then approximately 900

of them will contain the true mean . (D) There is a 90% probability that a data value, chosen at random, will fall in this interval.

(3) Which of the following will reduce the width of a confidence interval? (A) Increasing the confidence level.

(B) Increasing the sample size.

(C) Replace the sample proportion by 0.5.

(D) None of these will guarantee.

(4) The choice between a z-test and a t-test for a population mean depends primarily on:

(A) the level of significance.

(B) the sample size. (C) whether a one-tailed or two-tailed test is indicated. (D) whether the given standard deviation is from the population or the sample.

(5) In a hypothesis test, the decision between a one-tailed and a two-tailed test alternative hypothesis is based on:

(A) the level of significance.

(B) H1 appropriate for the context of the problem.

(C) which one gives a significant result.

(D) the statement of the null hypothesis.

(6) Your conclusion of a hypothesis testing is to reject the null hypothesis H0. Which of the following is true?

(A) The null hypothesis must be false.

(B) The alternative hypothesis must be true.

(C) A type I error is possible.

(D) A type II error is possible.

(7) If the P-value of a test is greater than the level of significance, then which of the following conclusions are appropriate?

I. The tests is inconclusive. II. Fail to reject the null hypothesis. III. The null hypothesis is true.

(A) I only

(B) II only

(C) III only

(D) II and III only

(8) To test if the mean number of hours spent working per week by college students who hold jobs is different from 15 hours, you write the null and alternative hypotheses as follows:

(A)H0 : = 15 vs. H1 : does not equal 15

(B)H0 : 15 vs. H1 : < 15

(C)H0 : 15 vs. H1 : > 15

(D)H0 : = 15 vs. H1 : > 15

(9) The rejection region for a test: H0 : p = 0.4 vs. H1 : p < 0.4, with n = 50 and = 0.05 is

(A)Reject H0 if z > 1.96 or z < 1.96.

(B)Reject H0 if z > 1.645 or z < 1.645.

(C)Reject H0 if z < 1.96.

(D)Reject H0 if z < 1.645.

(10) Suppose the P-value of the test is 0.0344. We can then conclude:

(A) At = 0.025, reject H0.

(B) At = 0.02, reject H0.

(C) At = 0.01, reject H0.

(D) At = 0.025, fail to reject H0