Question 1091477
Ho=no change
Ha=change
alpha=0.05
test statistic is (given normality and s an unbiased estimator of sigma) a t with df=24 
critical value is |t| > 2.064
calculation is t=(1.6-2)/1.5/sqrt(25)=-0.4*5/1.5=-2/1.5=-1.33
Fail to reject Ho; insufficient evidence to conclude that delivery has improved.