Refer to the Lincolnville school bus data. Set up a variable that divides the age of the buses into three groups: new (less than 5 years old), medium (at least 5 but less than 10 years), and old (10 or more years). The median maintenance cost is $4,179. Based on this value, create a variable for those less than or equal to the median (low maintenance) and those more than the median (high maintenance cost). Finally, develop a table to show the relationship between maintenance cost and age of the bus.

a. What percentage of the buses are less than five years old?

b. What percentage of the buses less than five years old have low maintenance costs?

c. What percentage of the buses ten or more years old have high maintenance costs?

d. Does maintenance cost seem to be related to the age of the bus? Hint: Compare the maintenance cost of the old buses with the cost of the new buses. Would you conclude maintenance cost is independent of the age?