Question #7

You are the operations manager for an airline and you are considering a higher fare level for passengers in aisle seats. How many randomly selected air passengers must you survey? Assume that you want to be 95% confident that the sample percentage is within

1.5 percentage points of the true population percentage. Complete parts (a) and (b) below.

a. Assume that nothing is known about the percentage of passengers who prefer aisle seats.

n = __________

(Round up to the nearest integer.)

b. Assume that a prior survey suggests that about 36% of air passengers prefer an aisle seat.

n = _________

(Round up to the nearest integer.)

Question #8

A clinical trial tests a method designed to increase the probability of conceiving a girl. In the study 435 babies were born, and 348 of them were girls. Use the sample data to construct a 99% confidence interval estimate of the percentage of girls born. Based on the result, does the method appear to be effective?

_________ < p < _________

(Round to three decimal places as needed.)

Does the method appear to be effective?

A. No, the proportion of girls isnot significantly different from 0.5.

B. Yes, the proportion of girls is significantly different from 0.5.

Question #9

Use the sample data and confidence level given below to complete parts (a) through (d).

A drug is used to help prevent blood clots in certain patients. In clinical trials, among 4636

patients treated with the drug, 140 developed the adverse reaction of nausea. Construct a 90% confidence interval for the proportion of adverse reactions.

a) Find the best point estimate of the population proportion p.

__________

(Round to three decimal places as needed.)

b) Identify the value of the margin of error E.

E = _________

(Round to three decimal places as needed.)

c) Construct the confidence interval.

__________ < p < ___________

(Round to three decimal places as needed.)

d) Write a statement that correctly interprets the confidence interval. Choose the correct answer below.

A. 90% of sample proportions will fall between the lower bound and the upper bound.

B. One has 90% confidence that the sample proportion is equal to the population proportion.

C. One has 90% confidence that the interval from the lower bound to the upper bound actually does contain the true value of the population proportion.

D. There is a 90% chance that the true value of the population proportion will fall between the lower bound and the upper bound.

Question #10

An IQ test is designed so that the mean is 100 and the standard deviation is 12 for the population of normal adults. Find the sample size necessary to estimate the mean IQ score of statistics students such that it can be said with 95% confidence that the sample mean is within 2 IQ points of the true mean. Assume that =12 and determine the required sample size using technology. Then determine if this is a reasonable sample size for a real world calculation.

The required sample size is _________.

(Round up to the nearest integer.)

Would it be reasonable to sample this number of students?

A. Yes. This number of IQ test scores is a fairly small number.

B. No. This number of IQ test scores is a fairly large number.

C. Yes. This number of IQ test scores is a fairly large number.

D. No. This number of IQ test scores is a fairly small number.