Does fast driving waste fuel? How does the fuel consumption of a car change as its speed increases? Here are data for a British Ford Escort. Speed is measured in kilometers per hour, and fuel consumption is measured in liters of gasoline used per 100 kilometers traveled.7 Speed

(km/h)

Fuel used

(liters/100 km)

Speed

(km/h)

Fuel used

(liters/100 km)

10 21.00 90 7.57 20 13.00 100 8.27 30 10.00 110 9.03 40 8.00 120 9.87 50 7.00 130 10.79 60 5.90 140 11.77 70 6.30 150 12.83 80 6.95

(a) Use your calculator to help sketch a scatterplot.

(b) Describe the form of the relationship. Why is it not linear?

Explain why the form of the relationship makes sense.

(c) It does not make sense to describe the variables as either positively associated or negatively associated. Why?

(d) Is the relationship reasonably strong or quite weak?

Explain your answer.