A certain pen has been designed so that true average writing lifetime under controlled conditions (involving the use of writing machine) is at least 10 hours. A random sample of 18 pens is selected,...

A certain pen has been designed so that true average writing lifetime under controlled conditions (involving the use of 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 support the use of a one-sample t test.What hypotheses should be tested if the investigators believe a priori that the design specification has been satisfied?What conclusion is appropriate if the hypotheses of part (a) are tested, t = -2.3, a = 0.05?What conclusion is appropriate if the hypotheses of part (a) are tested, t = -1.8, a = 0.01?What should be concluded if the hypotheses of part (a) are tested a = 0.1 and t = -3.6?