1. Correct. The answer is true
H0 : μ=1600, Ha: μ ≠ 1600. We should use a two-tailed tests because μ ≠ 1600 includes values both lager and smaller than 1600.
At a 5% level of significance, decision rule is to reject Ho if the z score is outside the range -1.96 to 1.96.
Under H0, m=1600 and using sample standard deviation as an estimate of s. Since Z=(`X-160)/12 = (1550-1600)/12=-4.1667 lies outside the range -1.96 to 1.96, we reject H0 at 5% level of significance.