8.11 A group of 20 mice are allocated to individual cages randomly. The cages are assigned in equal numbers, randomly, to two treatments, a control A and a certain drug B. All animals, in a random sequence, are infected with tuberculosis. The numbers of days until the mice die after infection are given as follows (one mouse in A got lost):

Control A: 5, 6, 7, 7, 8, 8, 8, 9, 12 Drug B: 7, 8, 8, 8, 9, 9, 12, 13, 14, 17 Since a preliminary experiment has established that the drug is not toxic, we can assume that the drug group cannot be worse (die sooner)

than the control group under any reasonable conditions. Test the null hypothesis that the drug is without effect at a significance level of 0.05 and briefly justify your choice of test.