Use the sample statistics from Exercise 29 and assume the number of vehicles in the sample is 75.
(a) Estimate the number of vehicles whose speeds are between 63 miles per hour and 71 miles per hour.
(b) In a sample of 25 additional vehicles, about how many vehicles would you expect to have speeds between 63 miles per hour and 71 miles per hour?
Use the Empirical Rule.
Exercise 29
The mean speed of a sample of vehicles along a stretch of highway is 67 miles per hour, with a standard deviation of 4 miles per hour. Estimate the percent of vehicles whose speeds are between 63 miles per hour and 71 miles per hour. (Assume the data set has a bell-shaped distribution.)