"Y" size batteries produced by YYZ Corporation have had a life expectancy of 87 hours.
A quality control expert wants to test whether the life expectancy of these batteries has changed from its past value of 87 hours. A sample of 36 batteries showed an average life of 88.5 hours and a standard deviation s = 8 hours.
a) Formulate the hypotheses for this problem.
b) Compute the test statistic.
c) Using = 0.05, perform the test using either the critical value approach or the p-value approach. What is your conclusion?