Scores of adults aged 60 to 64 on a common IQ test are approximately Normally distributed with mean 90 and standard deviation 15.
Suppose we call an IQ of 90 "normal" for adults aged 60 to 64. What percent of the population have "below normal" IQs?
A) About 50%
B) Less than 50%
C) More than 50%
D) Can't tell from the information given.

Question

Quizplus · Accepted Answer

In a normal distribution, the mean divides the distribution into two equal halves. Since an IQ of 90 is the mean, 50% of the population will have IQ scores below this value.

Scores of Adults Aged 60 to 64 on a Common