The distribution of the IQ Intelligence Quotient is approxim

The distribution of the IQ (Intelligence Quotient) is approximately normal in shape with a mean of 100 and a standard deviation of 15. According to the standard deviation rule, what range of IQ scores do many (68%) people have?

Solution

68% lie between 1 standard deviation above and below the mean. Hence,

u - sigma = 100 - 15 = 85
u + sigma = 100 + 15 = 115

hence, it is from 85 TO 115. [ANSWER]