Population distribution question for college statistics

Question

A population of values has a normal distribution with  and . You intend to draw a random sample of size .

Find P9, which is the score separating the bottom 9% scores from the top 91% scores.

Find P9, which is the mean separating the bottom 9% means from the top 91% means.

Enter your answers as numbers accurate to 1 decimal place. Answers obtained using exact z-scores or z-scores rounded to 3 decimal places are accepted.

I think I'm supposed to use inv here, but it keeps saying I'm wrong. I'm using inv( .91, 56.2, 82.6) (Don't have TI-84) and (.91, 56.2/Sqrt 223, 82.6) is this correct?



Answer 1

Your idea is right but you need to use 0.09 instead of 0.91 because this is the area to the left