2. Incorrect. The answer is true not false

H₀: μ =3100, H_a: μ≠3100. We should use a two-tailed test because μ≠3100 includes values both larger and smaller than 3100.

At a 5% level of significance, decision rule is to reject H_o if the z score is outside the range -1.96 to 1.96.

Under H₀, μ =3100 and using samples standard deviation as an estimate of σ. Since Z=(X_bar-μ₀)/(σ/√n)=(3200-3100)/(250/[25]) = 100/50=2.00, which lies outside the range -1.96 to 1.96, we reject H₀ at 5% level of significance. While it is close, the evidence suggests that the mean time until major repair is greater than 3,100 hours