Assume that adults have IQ scores that are normally distributed with a mean of 100 and a standard deviation of 15 (as on the Wechsler test). Find the IQ score separating the top 16% from the others.
A) 85.0
B) 108.1
C) 114.9
D) 99.1

Question

Quizplus · Accepted Answer

The top 16% corresponds to the 84th percentile. Using the standard normal distribution table or a calculator, the z-score for the 84th percentile is approximately 0.995. Using the formula for converting a z-score to an IQ score: IQ = mean + (z-score * standard deviation) = 100 + (0.995 * 15) = 114.925, which rounds to 114.9.

Assume That Adults Have IQ Scores That Are Normally Distributed