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.

x 0.75

The indicated IQ​ score, x, is ___

Answer 1

Given that,

mean = = 100

standard deviation = = 15

Using standard normal table,

P(Z < z) = 0.75

= P(Z < z) = 0.75

= P(Z <0.67 ) = 0.75

z = 0.67 Using standard normal z table,

Using z-score formula  

x= z * +

x= 0.67 *15+100

x= 110.05

x=110