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 were selected at each location on a particular day, and the waiting times were collected and stored – see dataset ERWaiting (the same dataset in both 13th and 14th edition, use either one). a) At the 0.05 level of significance, is there an evidence of a difference in the mean waiting times in the four locations? b) If appropriate, determine which pairs of locations differ in mean waiting time. c) At the 0.05 level of significance, is there an evidence of a difference in the variation in waiting times among the four locations?