For Exercises 2.23 and 2.24, see page 75; and for 2.25 and 2.26, see pages 77–78.

Question 2.38

2.38 Consider the fuel type

Refer to the previous exercise and to Figure 2.6 (page 71), where different colors are used to distinguish four different types of fuels used by these vehicles.

canfuel

  1. Make a figure similar to Figure 2.6 that allows us to see the categorical variable, type of fuel, in the scatterplot. If your software does not have this capability, make different scatterplots for each fuel type.
  2. Discuss the relationship between highway MPG and city MPG, taking into account the type of fuel. Compare this view with what you found in the previous exercise where you did not make this distinction.
  3. Find the correlation between highway MPG and city MPG for each type of fuel. Write a short summary of what you have found.