Question

 Find the indicated IQ score. The graph to the right depicts IQ scores of adults, and those scores are normally distributed with a mean of 100 and a standard deviation of 15. 

Click to view page 1 of the table. Click to view page 2 of the table. 

The indicated IQ score, x, is _______ .

Answer 1

Solution :

Given that,

P(Z > z) = 0.99

1 - P( Z < z) = 0.99

P(Z < z) = 1 - 0.99

P(Z < z) = 0.01

z = - 2.33

Using z-score formula,

x = z * $\sigma$ + $\mu$

x = - 2.33 * 15+ 100

x =65.1