Fuel Economy. Refer to the following table of fuel economy data for a sample of 10 vehicles for Exercises 80–84. The predictor variable is , expressed in liters; the response variable is , expressed in miles per gallon (mpg).

Vehicle
Mini Cooper 1.6 31
Ford Focus 2.0 28
Toyota Camry 2.5 26
Honda Accord 2.4 26
Subaru Forester 2.5 23
Toyota Highlander 2.7 22
Ford Taurus 3.5 20
Chevrolet Equinox 3.0 19
Dodge Nitro 4.0 17
Cadillac limousine 4.6 14

Question 4.179

enginempg

81. What Results Do You Expect? Based on your scatterplot in Exercise 80, answer the following:

  1. Will the correlation coefficient be positive or negative?
  2. Do you expect that the correlation will be closer to −0.9 or −0.5? Why?
  3. Do you think that the slope will be positive or negative? Why?

4.2.81

(a) Negative; (b) 20.9; the dots lie in a pattern that is close to a straight line (c) Negative; the dots lie in a pattern that is close to a straight line with a negative slope.