Question

@phi @mathmale

Answer 1

Do i use the Zscore formula here? and is there another way than Zscore formula?

Answer 2

yes, you use a z-score. In math there are probably lots of ways to doing the same thing i.e. use calculus or numerical integration. But the z-score idea is the easiest and fastest way.

Answer 3

Great i used it and the answer was for the 5% will have zscores for greater than or equal to 1.65 is that correct?

Answer 4

yes, I get 1.645
using
http://davidmlane.com/hyperstat/z_table.html

Answer 5

Thank you

Answer 6

But the question sounds like they want more detail. For example, say
multiply the standard deviation by 1.645 and then add that to the mean of the population to find the top 5%