Suppose that the IQ scores of a certain population have an a

Suppose that the IQ scores of a certain population have an approximate normal distribution with mean 100.8 and standard deviation 14.3. What fraction of the population has an IQ score less than 120.5?

Solution

Let X be the IQ scores

mu = 100.8 and sigma =14.3

For finding the fraction we have to find the prob for X< 120.5

z score = 120.5-100.8/14.3 = -1.38

Prob = 0.4162

Hence 41.62% of the population is answer