1. The scatterplot below shows the fuel efficiency (in
miles per gallon) and weight (in pounds) of
twenty subcompact cars.
91
3000
(a) Is there a clear explanatory variable and
response variable in this setting? If so, tell
which is which. If not, explain why not.
Car weight
(b) Does the scatterplot show a positive association, negative association, or neither? Explain why this
makes sense.
(c) How would you describe the form of the relationship?
(d) Which of the following is closest to the correlation between car weight and fuel efficiency for these
20 vehicles? Explain.
r=-0.9
r=-0.6
r=0 r=0.4
(e) There is one "unusual point" on the graph. Explain what is "unusual" about this car.
(
What effect would removing the “unusual point” have on the correlation? Justify your answer.
(g) If we converted the car weights to metric tons (1 metric ton -2,205 pounds). How would the
correlation change? Explain.
