Find the probability

Question

assume that adults have IQ scores that are normally distributed with a mean of 105 and a standard deviation of 15. Find the probabilty hat a randomly selected adult has an IQ between 90 and 120. 

 

the probability that a randomly selected adult has an IQ between 90 and 120 is ______

Answer 1

Hi again Kate,

 

for 90, the z score is (90 - 105)/15 = -1.00

 

for 120, the z score is (120 - 105)/15 = 1.00

 

prob(-1.00<z<1.00) = .8413 - .1587 = .6826