Mean score of 100, standard deviation of 15.

Question

What score needed to fall in the top 20%? What score needed to fall in the bottom 33%? 

 

 

Answer 1

For top 20% the z score value is 0.8415

  ( The values of z score taken from z score table )

Mean score = 100   standard deviation = 15

x-100 = 12.6225

x=112.6225

For bottom 33% the z score value is 0.4399

x-100 = 6.5985

x = 106.5985