Chapter 9, Problem 9.78CRP

An experimenter wants to study the relationship between type of milk and infant growth in underdeveloped countries. She randomly assigns 300 infants to either a breast-feeding group or an infant formula group. She then weighs the infants every three days for the first four weeks of life.

A team of UMD students have invented an inhalable drug that they think will help people breathe better during hard exercise. They test the drug on 3 volunteers (A, B, and C) by measuring their levels of arterial oxygen before receiving the drug (their base level) and then after 5 and 10 minutes have elapsed, respectively. The results are listed in the table. Oxygen level [mmHg] A B C base level 847076 after 5 minutes 85 74 81 after 10 minutes 90 75 98 We want to see how the drug work (better or worse) when compared to the base level. Compute the 90% two-sided confidence intervals for the mean difference between the base level and after 5 minutes. X1b Xub X 1b -5.1783 Xub 11.8450 Compute the 90% two-sided confidence intervals for the mean difference between the base level and after 10 minutes. -1.94 ? Xx 0% 23.94 ? × 0% ? × 0% X 0%

Some commercial airlines recirculate about half the air in the cabin during flights as a way to improve fuel efficiency. Other airlines make a policy of NOT recirculating the air and instead, have fresh air from the atmosphere constantly being inserted into the cabin with the “old” air being pumped out of the plane. A total of 1100 passengers flying from San Francisco to Denver were used for an experiment. After their flight, they were each given a list of symptoms associated with the common cold. They were asked to report if they experienced cold symptoms within 24 hours of the flight landing. Of the 517 passengers who flew on planes that recirculate the air, 108 reported post-flight cold symptoms. Of the 583 passengers who flew on airlines that do not use recirculation in the cabin, 110 reported symptoms. Suppose now that we want to use the recirculation of air data to explore “Goal #2”, which is to resolve a hypothesis test about . a) If we want to resolve this hypothesis…