The table below, a subset of the data given in Exercise 3.33, shows the gestation time in days and the average longevity in years for a variety of mammals in captivity.4

a. If you want to estimate the average longevity of an animal based on its gestation time, which variable is the response variable and which is the independent predictor variable?
b. Assume that there is a linear relationship between gestation time and longevity. Calculate the least-squares regression line describing longevity as a linear function of gestation time.
c. Plot the data points and the regression line. Does it appear that the line fits the data?
d. Use the appropriate statistical tests and measures to explain the usefulness of the regression model for predicting longevity.

Gestation Avg Longevity Bear (black) Cat (domestic) Goat (domestic) 151 Monkey (rhesus 66 Mouse (meadow) Sheep (domestic) 154