2

Problem 2. An experiment is conducted to determine whether vampire bats prefer blood at room temperature or at body temperature. Two groups of 40 bats are given access for a day to drinking tubes attached to supply of blood kept at either one of the two temperatures: one group of bats has access only to blood at body temperature while the other group has access to blood at the other temperature setting. For each bat we record the average amount of blood (in grams) that the bat drinks. We want to test whether the average amount of room- temperature and body-temperature blood consumed are equal. The 40 bats drinking blood at body temperature drank an average of 23.8 grams of blood with a standard deviation of 3.1 grams; while the other 40 vampire bats drank an average of 27.4 grams of blood with a standard deviation of 4.6 grams. Conduct the test at the 0.05 significance level