If an IQ distribution is normal and has a mean of 100 and a standard deviation of 15, then 68% of all those taking the test scored between IQ's of
A) 100 and 115
B) 85 and 100
C) 92.5 and 107.5
D) 85 and 115

Question

Quizplus · Accepted Answer

In a normal distribution, 68% of the data falls within one standard deviation of the mean. Since the mean is 100 and the standard deviation is 15, one standard deviation below the mean is 85 (100-15) and one above is 115 (100+15), thus 68% of scores fall between 85 and 115.

If an IQ Distribution Is Normal and Has a Mean