Cancer treatment using chemotherapy employs chemicals that

Chapter 15, Problem 28E

(choose chapter or problem)

Cancer treatment using chemotherapy employs chemicals that kill both cancer cells and normal cells. In some instances, the toxicity of the cancer drug—that is, its effect on normal cells— can be reduced by the simultaneous injection of a second drug. A study was conducted to determine whether a particular drug injection was beneficial in reducing the harmful effects of a chemotherapy treatment on the survival time for rats. Two randomly selected groups of rats, 12 rats in each group, were used for the experiment. Both groups, call them A and B, received the toxic drug in a dosage large enough to cause death, but group B also received the antitoxin that was intended to reduce the toxic effect of the chemotherapy on normal cells. The test was terminated at the end of 20 days, or 480 hours. The lengths of survival time for the two groups of rats, to the nearest 4 hours, are shown in the following table. Do the data provide sufficient evidence to indicate that rats receiving the antitoxin tended to survive longer after chemotherapy than those not receiving the antitoxin? Use the Mann–Whitney U test with a value of α near .05.