Shankaran and colleagues (2012) reported the results of a randomized trial of whole-body hypothermia (cooling) for neonatal hypoxic–ischemic encephalopathy (brain problems in babies due to lack of oxygen). Twenty-seven of the 97 infants randomly assigned to hypothermia died and 41 of the 93 infants in the control group died.

a. Find and compare the sample percentages that died for these two groups.

b. Test the hypothesis that the death rate was less for those treated with hypothermia at a 0.05 significance level.