9 Scores on the test are normally distributed with a mean of

9. Scores on the test are normally distributed with a mean of 63.2 and a standard deviation of 11.7. Find Pa, which separates the bottom 81% from the top 19%.

Solution

we have to find the score for p81 from the top 19

hence the z-score for P81 = 0.878
therefore the score = 63.2 + 0.878*11.7 = 73.34