Assume that adults have IQ sources that are normaly distrubu

Assume that adults have IQ sources that are normaly distrubuted with a mean of 102 and a deviation of 15. Find the third quartle Qs, Which is the IQ source separating the top 25% from the others. The third quartle Qs is (Round to one decimal place as needed. )

Solution

Mean =102 and std dev = 15

For normal distribution iii quartile is c such that

P(X<=C\') = P(Z<=c)=0.75

From normal table

c =0.675

Hence corresponding x value = C\' = 102+0.675(15)

= 102+10.125

112.125.

Q3 = 112.125