Gestation.

For women, pregnancy lasts about 9 months. In other species of animals, the length of time from conception to birth varies. Is there any evidence that the gestation period is related to the animal s lifespan? The first scatterplot shows Gestation Period (in days) vs. Life Expectancy (in years) for 18 species of mammals. The highlighted point at the far right represents humans.

a) For these data, r = 25, not a very strong relationship. Do you think the association would be stronger or weaker if humans were removed? Explain.

b) Is there reasonable justification for removing humans from the data set? Explain.

c) Here are the scatterplot and regression analysis for the 17 nonhuman species. Comment on the strength of the association.

d) Interpret the slope of the line.

e) Some species of monkeys have a life expectancy of about 20 years. Estimate the expected gestation period of one of these monkeys.