Chapter 12, Problem 67H

Recently, the annual number of driver deaths per 100,000 for the selected age groups was as follows:

Age	Number of Driver Deaths per 100,000
16-19	38
20-24	36
25-34	24
35-54	20
55-74	18
75+	28

Table 12.19

a. For each age group, pick the midpoint of the interval for the x value. (For the 75+ group, use 80.)

b. Using “ages” as the independent variable and “Number of driver deaths per 100,000” as the dependent variable,

make a scatter plot of the data.

c. Calculate the least squares (best−fit) line. Put the equation in the form of: $\hat{y}\text{=}a+bx$

d. Find the correlation coefficient. Is it significant?

e. Predict the number of deaths for ages 40 and 60.

f. Based on the given data, is there a linear relationship between age of a driver and driver fatality rate?

g. What is the slope of the least squares (best-fit) line? Interpret the slope.