Assuming the normality assumption is valid,

(a) test ????0 ∶ ????0 = 25 at the ???? = 0.05 level when ˆ????0 = 23.5, ????????(ˆ????0) = 1.39, and

???? = 25.

(b) approximate the ????-value associated with the value of ???????????????? in part (a).

(c) determine whether or not there is sufficient evidence to reject ????0 ∶ ????0 = 25 at the ???? = 0.05 level.

(d) Compute a 95% confidence interval for ????0.