Use the Empirical Rule. The mean speed of a sample of vehicles along a stretch of highway is 64

with a standard deviation of 5 miles per hour. Estimate the percent of vehicles whose speeds are between 54 miles per hour and 74(Assume the data set has abell-shaped distribution.)

Approximately % of vehicles travel between 54 miles per hour and 74 miles per hour.

The numbers of courses taught per semester by a random sample of university professors are shown in the histogram. Make a frequency distribution for the data. Then use the table to estimate the sample mean and the sample standard deviation of the data set.

Make a frequency distribution for the data.

x f

1

2

3

4

n

u 25

m 20

b 15

e 10 2 17 21 18

r 5

of 0 1 2 3 4

professor number of course taught per semester