The amount of monthly rainfall varies from month to month and from city to city. Applied Example 12.5 suggests that the average monthly rainfall is affected by both the month and the location.

a. What variable was used to collect the data used to find the monthly averages shown in Applied Example 12.5?

b. Explain what data would be needed and how it would be arranged to analyze the location

(represented by cities) effect on the amount of rainfall during the month of April.