Question

For males in a certain town, the systolic blood pressure is normally distributed with a mean of 125 and a standard deviation of 5. Using the empirical rule, determine the interval of systolic blood pressures that represent the middle 68% of males.

Answer 1

By the empirical rule (68–95–99.7), about 68% lie within one standard deviation of the mean.
So the interval is 125 ± 5 = [120, 130] mm Hg.