Question

in a certain normal distribution , 1.25% of the area lies to the left of 42 , and 1.25% of the area lies to the right of 48. find population mean and sigma

Answer 1

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.0125) and its Z score.

Z = ±2.24

Mean = (48-42)/2 = ?

Z = (score-mean)/SD

Insert values for Z, score and mean to solve for SD (sigma).

Answer 2

I almost didn't answer your post, because "statics" relates to physics. If you want to shorten statistics, stats would be better.