The file P9_7.XLS contains salary data on over 1400 NFL footbal players in the 1990 season. We want to use a chi-square test of independence to see whether Salary is related to other variables in the data set, such as the conference (NFC or AFC) or the player’s position (quarterback, running back, and so on). Because the chi-square test requires categorical variables, you must first divide all salaries into several categories. Use the categories (in $1000s): less than 200, 200 to 400, 400 to 600, and greater than 600. Then test whether the following variables are independent. If they are not, discuss the type of dependence that appears to exist.

a. Salary and NFC (coded 1 for NFC, 0 for AFC)

b. Salary and Offense (coded 1 for offense, 0 for defense)

c. Salary and Position d Salary and Team