A 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 hr. 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. The relevant hypotheses are H0: μ = 10 versus Ha: μ < 10. (a) If t = -2.5 and α = .05 is selected, what conclusion is appropriate?