Question #2: Regarding the fuel type variable, the value “d” represents diesel, “p” represents premium (petrol) and “r” represents regular (petrol). Do you think there is an effect of fuel type on how many miles a vehicle can run on average per gallon of fuel?

ggplot(data = mpg) + geom_point(mapping = aes(x = fl, y = hwy), position = "jitter")

Answer: According to the figure, the fuel type seems to have some association with the miles per gallon a car can drive. In which, “d” diesel and

Question #3: Do you think there is a difference in fuel economy for vehicles made in 1999 and 2008? (When plotting with “year” variable, use as.factor(year) to convert it to categorical variables. This will be explained in future classes.)

Question #4: What happens if you make a scatter plot of class vs drv? Do you think this plot is useful or not?