The scatterplot shows, for 2015 cars, the carbon footprint (tons of CO₂ per mile) vs. the new Environmental Protection Agency (EPA) highway mileage for 69 family sedans as reported by the U.S. government (www.fueleconomy.gov/feg/byclass.htm); the cars in the lower right of the scatterplot plotted in red are all hybrids.

a) The correlation is -0.860. Describe the association.

b) Are the assumptions and conditions met for computing correlation?

c) Using technology, find the correlation of the data when the hybrid cards are not included with the others. Can you explain why it changes in that way?

375 300 225 150 + 30 25 35 40 45 Highway Carbon Footprint (CO/mile)