Use the Empirical Rule. The mean speed of a sample of vehicles along a stretch of highway is 68 miles per hour, with a standard deviation of 5 miles per hour. Estimate the percent of vehicles whose speeds are between 58

miles per hour and 78 miles per hour. (Assume the data set has a bell-shaped distribution.)

Approximately what % of vehicles travel between 58 miles per hour and 78 miles per hour?