Question: Finding Test Components. In Exercises 13 and 14, assume that a simple random sample has been selected from a normally distributed population. Find the null and alternative hypotheses, test statistic, P-value (or range of P-values), critical value(s), and state final conclusion.

Claim: The mean life span of desktop PCs is less than 7 years.

Sample data: n = 21, \(\bar{X}\) = 6.8 years, s = 2.4 years. The significance level is a = 0.05.