wA certain pen has been designed so that true average writing lifetime under controlled conditions (involving the use of a writing machine) is at least 10 hours. A random sample of 18 pens is selected, the writing lifetime of each is determined, and a normal probability plot of the resulting data supports the use of a one-sample t test. The relevant hypotheses are H0: µ = 10 versus Ha: µ <
10.
a. If t = - 2.3 and a = .05 is selected, what conclusion is appropriate?
b. If t = - 1.83 and a = .01 is selected, what conclusion is appropriate?
c. If t = 0.47, what conclusion is appropriate?