Question 1168096
the half-interval is 1.96*200/sqrt(90), and that is added to and subtracted from, the mean.
that is 41.32, so yes, you are correct.

same approach--the half-interval is 1.96*1.12/sqrt(60)=0.2834
the interval is 1.5+/-0.28 or (1.22, 1.78) units cavities