Question

2. A university dean of students wishes to estimate the average number of hours students spend doing homework per week. The standard deviation form a previous study is 6.2 hours. How large a sample must be selected if he wants to be 99% confident of finding whether the true mean differs from the sample mean by 1.5 hours?

Answer 1

You can play around with Z table stuff at
davidmlane.com/hyperstat/z_table.html