If the age distribution of customers at a major retail chain is thought to be bell-shaped with a mean equal to 43 years and a standard deviation equal to 7 years, the percentage of customers between the ages of 29 and 57 years is:
A) approximately 81.5.
B) approximately 68.
C) at least 75.
D) approximately 95.

Question

Quizplus · Accepted Answer

This scenario describes a normal (bell-shaped) distribution, where the empirical rule (68-95-99.7 rule) applies. According to this rule, approximately 95% of the data falls within two standard deviations of the mean. Here, two standard deviations from the mean (43 ± 2*7) gives us the range from 29 to 57 years, hence about 95% of the customers fall within this age range.

If the Age Distribution of Customers at a Major Retail