Assume the IQ scores are normally distributed with a mean of

Assume the IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. Find the probability that a randomly selected person has an IQ less than 115.

Solution

Normal Distribution
Mean ( u ) =100
Standard Deviation ( sd )=15
Normal Distribution = Z= X- u / sd ~ N(0,1)                  
P(X < 115) = (115-100)/15
= 15/15= 1
= P ( Z <1) From Standard Normal Table
= 0.8413