A hospital conducted a study of the waiting time in its ­emergency room. The hospital has a main campus and three ­satellite locations. Management had a business objective of reducing waiting time for emergency room cases that did not require immediate attention. To study this, a random sample of 15 emergency room cases that did not require immediate attention at each location were selected on a particular day, and the waiting times (measured from check in to when the patient was called into the clinic area) were collected and stored in ER Waiting.

a. At the 0.05 level of significance, is there evidence of a difference in the mean waiting times in the four locations?

b. If appropriate, determine which locations differ in mean ­waiting time.

c. At the 0.05 level of significance, is there evidence of a ­difference in the variation in waiting time among the four locations?