Assume that adults have IQ scores tha are normally distribut

Assume that adults have IQ scores tha are normally distributed with a mean of 105 and a standard deviation of 20. Find P₄ which is the IQ score separating the bottom 4% frm the top 96%.

(round to the nearest hundreth as needed)

Solution

P(X<c)=0.04

--> P((X-mean)/s <(c-105)/20) =0.04

--> P(Z<(c-105)/20) =0.04

--> (c-105)/20 =-1.75 (from standard normal table)

So c= 105-1.75*20 =70