Behavior of pet  owners

On the morning of March 5, 1996, a train with 14 tankers of propane derailed near the center of the small Wisconsin town of Weyauwega. Six of the tankers were ruptured and burning when the 1700 residents were ordered to evacuate the town. Researchers study disasters like this so that effective relief efforts can be designed for future disasters. About half of the households with pets did not evacuate all of their pets. A study conducted after the derailment focused on problems associated with retrieval of the pets after the evacuation and characteristics of the pet owners. One of the scales measured "commitment to adult animals," and the people who evacuated all or some of their pets were compared with those who did not evacuate any of their pets. Higher scores indicate that the pet owner is more likely to take actions that bene?t the pet.37 Here are the data summaries:

Total calories                  2821 ± 44                2844 ± 48

Alcohol (grams)            0.24 ± 0.06              0.39 ± 0.11

(a) What does "se" stand for? Give x and s for each of the four sets of measurements.

(b) Is there signi?cant evidence at the 5% level that conductors consume more calories per day than do drivers? Use the two-sample t method to give a P-value, and then assess signi?cance.

(c) How signi?cant is the observed difference in mean alcohol consumption? Use two-sample t methods to obtain the P-value.

(d) Give a 95% con?dence interval for the mean daily alcohol consumption of London doubledecker bus conductors.

(e) Give a 99% con?dence interval for the difference in mean daily alcohol consumption between drivers and conductors.