Assignment:
Assume that the two samples are independent simple random samples selected from normally distributed populations. Do not assume that the population standard deviations are equal, unless your instructor stipulates otherwise.
Hypothesis Test for Braking Distances of Cars Refer to the sample data given in Exercise and use a 0.05 significance level to test the claim that the mean braking distance of four-cylinder cars is greater than the mean braking distance of six-cylinder cars.
Exercise
Confidence Interval for Braking Distances of Cars A simple random sample of 13 four-cylinder cars is obtained, and the braking distances are measured. The mean braking distance is 137.5 ft and the standard deviation is 5.8 ft. A simple random sample of 12 six cylinder cars is obtained and the braking distances have a mean of 136.3 ft with a standard deviation of 9.7 ft (based on Data Set 16 in Appendix B). Construct a 90% confidence interval estimate of the difference between the mean braking distance of four-cylinder cars and the mean braking distance of six-cylinder cars. Does there appear to be a difference between the two means?