Chapter 12, Problem 68H

Table 12.20 shows the life expectancy for an individual born in the United States in certain years.

Year of Birth	Life Expectancy
1930	59.7
1940	62.9
1950	70.2
965	69.7
1973	71.4
1982	74.5
1987	75
1992	75.7
2010	78.7

Table 12.20a. Decide which variable should be the independent variable and which should be the dependent variable.

b. Draw a scatter plot of the ordered pairs.

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

d. Find the correlation coefficient. Is it significant?

e. Find the estimated life expectancy for an individual born in 1950 and for one born in 1982.

f. Why aren’t the answers to part e the same as the values in Table 12.20 that correspond to those years?

g. Use the two points in part e to plot the least squares line on your graph from part b.

h. Based on the data, is there a linear relationship between the year of birth and life expectancy?

i. Are there any outliers in the data?

j. Using the least squares line, find the estimated life expectancy for an individual born in 1850. Does the least

squares line give an accurate estimate for that year? Explain why or why not.

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