A recent study in the Journal of the American Medical Association (February 2 0 , 2008) found that patients who go into cardiac arrest while in the hospital are more likely to die if it happens after 11 pm. The study investigated 58,593 cardiac arrests during the day or evening. Of those, 11,604 survived to leave the hospital. There were 28,155 cardiac arrests during the shift that began at 11 pm, com m only referred to as the graveyard shift. Of those, 4,139 survived for discharge. The following contingency table summarizes the results of the study:

a. Specify the competing hypotheses to deter mine whether a patient's survival depends on the time at which he/she experiences cardiac arrest.

b. Calculate the value of the test statistic.

c. At a 1% significance level, what is the critical value?

d. What is the conclusion to the statistical test? Is the timing of when a cardiac arrest occurs independent of whether or not the patient survives for discharge? Given your answer, what type of recommendations might you give to hospitals?