Question

Use the following information for the next 7 problems:

A simple random sample of 40 recorded speeds is obtained from cars traveling on a section of interstate 405 in Los Angeles. The sample has a mean of 68.4 miles per hour and a standard deviation of 5.7 miles per hour.

We wish to test the hypothesis that the mean speed of cars on this stretch of road is higher than the posted speed limit of 65 miles per hour. Test at a 0.5 level.

Question 15: What do yoy need to write down for the DATA SUMMARY of this problem?

A. sample size, number of successes, sample proportion

B. Sample size, sample mean, standard deviation

C. sample size, sample mean, population standard deviation

Question 16: Which of the following decribes the null and alternation hypothesis for this problem:

A. H0 u = 65, H1 u > 65

B. H0 u =68.4, H1 u <68.4

C. H0 u = 65, H1 u =/ 65

D. H0 u =68.4, H1 u =/ 68.4

Question 17: Which command in stat crunch do you use here?

A. z stats

B. T stats

C. Proportion stats

D. variance stat

Question 18: What is the p-value for this problem?

A. 0.05

B. 0.006

C. 0.003

D. 0.997

Question 19: do we reject the null hypothesis at the 0.05 level here?

A. Yes

B. No

Question 20: In plain english, what is the conclusion to the hypothesis test here?

A. the population mean speed is 68.4 MPH

B. The population mean speed is less than 68.4 MPH

C. The population mean speed is not 65 MPH

D. The population mean speed is faster that 65 MPH

Question 21: Calculate the 90% confidence interval estimate for the mean speed on I 405 in Los Angleles. We are 90% confident that the mean speed on I 405 is between 66.9 MPH and __________?

Answer 1