A statistics teacher believes that the final exam grade for her elementary stats class have a normal distribution with a mean of 82 and a standard deviation on 8.

Question

Find the score which separates the top 10% of the scores from the lowest 90% of the scores.

Answer 1

z-score for 90
= (90-82)/8 = 1

so don't even have to go to tables or charts, we are 1 standard deviation from 82, so
a score of 90 will do it