A study noted that the mean shelf-life for a sample of 39 TI-84 calculators is 15 years, in contrast to the mean of 13 years for regular calculators. Assuming that the 39 TI-84 calculators have shelf-lives with a standard deviation of 4.5 years, use a 0.05 significance level to test the claim that TI-84 calculators have a mean shelf-life that is greater than 13 years. a. Find the test statistic t. B. Find the critical value. C.What is the conclusion about the null hypothesis (reject or fail to reject)? d. What is the final conclusion in nontechnical terms