# A large factory that builds machines has three shifts, one that starts at 4:00 A.M., one that starts at noon, and one that starts at 8:00 P.M. The manager of the factory wanted to know whether there is an association between an employee’s work experience (less than five years with the company, between five and twenty years with the company, over twenty years with the company) and the time of the employee’s shift. The manager selected a random sample of 125 employees and classified employees by their shift time and work experience. Which of the following is an appropriate pair of hypotheses for the manager to use? A) H0 : Work experience is independent of the time of an employee’s shift. Ha : Work experience is dependent on the time of an employee’s shift. B) H0 : Employees with over 20 years of experience are just as likely to start work at 8 P.M. Ha : Employees with over 20 years of experience are less likely to start work at 8 P.M. C) H0 : There is an association between work experience and an employee’s shift. Ha : There is no association between work experience and an employee’s shift. D) H0 : For each shift, there is no difference between the proportions of work experience level. Ha : For each shift, there is a difference between the proportions of work experience level. E) H0 : Among those in the sample, the proportion of employees for each work experience level did not differ by shift. Ha : Among those in the sample, the proportion of employees for each work experience level did differ by shift.

A large factory that builds machines has three shifts, one that starts at 4:00 A.M., one that starts at noon, and one that starts at 8:00 P.M. The manager of the factory wanted to know whether there is an association between an employee’s work experience (less than five years with the company, between five and twenty years with the company, over twenty years with the company) and the time of the employee’s shift. The manager selected a random sample of 125 employees and classified employees by their shift time and work experience. Which of the following is an appropriate pair of hypotheses for the manager to use?

A) H0 : Work experience is independent of the time of an employee’s shift.

Ha : Work experience is dependent on the time of an employee’s shift.

B) H0 : Employees with over 20 years of experience are just as likely to start work at 8 P.M.

Ha : Employees with over 20 years of experience are less likely to start work at 8 P.M.

C) H0 : There is an association between work experience and an employee’s shift.

Ha : There is no association between work experience and an employee’s shift.

D) H0 : For each shift, there is no difference between the proportions of work experience level.

Ha : For each shift, there is a difference between the proportions of work experience level.

E) H0 : Among those in the sample, the proportion of employees for each work experience level did not differ by shift.

Ha : Among those in the sample, the proportion of employees for each work experience level did differ by shift.

## Answer

Answer: A) H0 : Work experience is independent of the time of an employee’s shift.

Ha : Work experience is dependent on the time of an employee’s shift.

Explanation: The chi-square test for independence tests whether two categorical variables are independent. The null hypothesis states that the variables are independent, and the alternative hypothesis states that they are dependent.