In a given population the mean IQ is 100 and the standard deviation is 15 points. What percent of that population should have an IQ that falls between 85 and 115?
A) 33
B) 51
C) 68
D) 77

Question

Quizplus · Accepted Answer

According to the empirical rule of normal distribution, approximately 68% of the population falls within one standard deviation (plus or minus) of the mean. Therefore, the percentage of the population with an IQ between 85 and 115 can be calculated as follows:

Proportion within one standard deviation = 68%

Proportion below 85 IQ = 50% - (68%/2) = 16%

Proportion beyond 115 IQ = 50% - (68%/2) = 16%

Therefore, the proportion within 85 and 115 IQ is 68% - 16% - 16% = 36%. So, approximately 36% of the population should have an IQ between 85 and 115.

In a Given Population the Mean IQ Is 100 and the Standard