A cell phone manufacturer claims that its phone will last for more than 8 hours of continuous talk time when the battery is fully charged. To test this claim a sample of n = 18 phones were tested. The results showed a sample mean of 8.2 hours and a sample standard deviation of 0.4 hour.
a. Conduct the hypothesis test using a 0.05 level of significance and determine whether or not the company's claim is supported?
b. Construct a 95% confidence Interval estimate of the population mean?