Question #12

In a study of the accuracy of fast food drive-through orders, Restaurant A had 255 accurate orders and 74 that were not accurate.

a. Construct a 95% confidence interval estimate of the percentage of orders that are not accurate.

b. Compare the results from part (a) to this 95% confidence interval for the percentage of orders that are not accurate at Restaurant B: 0.203 < p < 0.294. What do you conclude?

a. Construct a 95% confidence interval. Express the percentages in decimal form.

__________ < p < __________ (Round to three decimal places as needed.)

b. Choose the correct answer below.

A. The lower confidence limit of the interval for Restaurant B is higher than the lower confidence limit of the interval for Restaurant A and the upper confidence limit of the interval for Restaurant B is also higher than the upper confidence limit of the interval for Restaurant A. Therefore, Restaurant B has a significantly higher percentage of orders that are not accurate.

B. Since the upper confidence limit of the interval for Restaurant B is higher than both the lower and upper confidence limits of the interval for Restaurant A, this indicates that Restaurant B has a significantly higher percentage of orders that are not accurate.

C. Since the two confidence intervals overlap, neither restaurant appears to have a significantly different percentage of orders that are not accurate.

D. No conclusion can be made because not enough information is given about the confidence interval for Restaurant B.

Question #13

A clinical trial was conducted to test the effectiveness of a drug for treating insomnia in older subjects. Before treatment, 16 subjects had a mean wake time of 103.0 min. After treatment, the 16 subjects had a mean wake time of 93.1 min and a standard deviation of

22.8 min. Assume that the 16 sample values appear to be from a normally distributed population and construct a 99% confidence interval estimate of the mean wake time for a population with drug treatments. What does the result suggest about the mean wake time of 103.0 min before the treatment? Does the drug appear to be effective?

Construct the 99% confidence interval estimate of the mean wake time for a population with the treatment.

___________ min < < _________ min

(Round to one decimal place as needed.)

What does the result suggest about the mean wake time of 103.0 min before the treatment? Does the drug appear to be effective?

The confidence interval ____________ ( A. does not include, B. includes ) the mean wake time of 103.0 min before the treatment, so the means before and after the treatment _____________ ( A. could be the same, B. are different ) This result suggests that the drug treatment ____________ ( A. has, B. does not have ) an effect.

Question #14

An IQ test is designed so that the mean is 100 and the standard deviation is 10

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 =10 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 small 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 large number.