In a bit of good news for male students, based on 2014 data, American men have closed the gap with women on life span, according to the Population Reference Bureau

(source: “Life expectancy at birth, by gender, 1970 and 2014,” www.prb.org/DataFinder). Male life expectancy attained a record 76 years, and women’s reached 81 years. The Population Reference Bureau provided the data given in the file titled LifeExpectancy.

a. Produce a scatter plot depicting the relationship between the life expectancies of women and men.

b. Determine the order of the polynomial that is represented on the scatter plot in part

a. Produce the estimated regression equation that represents this relationship.

c. Determine if women’s average life expectancy can be used in a second-order polynomial to predict the average life expectancy of men. Use a significance level of 0.05.

d. Use the estimated regression equation computed in part b to predict the average length of life of men when women’s length of life equals 100. What does this tell you about the wisdom (or lack thereof) of extrapolation in regression models?