One of the major measures of the quality of service provided by a hospital is the speed with which it attends to its emergency room patients. The file ER contains a random sample of waiting times of 70 patients in emergency rooms at various hospitals across Eastern Europe.

a. The CEO of the hospital claims that the mean waiting time of patients at the ER is 35 minutes. At the 0.05 level of significance, is there evidence that the claim is not true (i.e., the mean number of minutes is different from 35)?

b. What assumption about the population distribution is needed in order to conduct the \(t\) test in (a)?

c. Construct a boxplot or a normal probability plot to evaluate the assumption made in (b).

d. Do you think that the assumption needed in order to conduct the \(t\) test in (a) is valid?