Question: An experiment was concerned with the possible effect of a small lesion in a particular area of a hamsters brain on the activity level of the animal. 30 hamsters were selected at random and randomly divided into two groups of 15 animals each. Group 1 was used as a control and given no lesion, whereas group 2 was given a lesion in the designated area. Because 3 animals died in group 2, the actual number turned out to be 12 for that group. After full recovery by the remaining hamsters, each was given access to a running wheel, and the number of revolutions per fixed unit time was recorded. The following data show activity in hundreds of revolutions per unit time. Did the lesion produce a significant difference in activity between the two groups (α=.01)? Construct the 99% confidence interval around the mean difference.

Group 1> \(\bar{X}\) = 9.26

s =1.45

n = 15

Group 2> \(\bar{X}\) = 5.14

s = 2.81

n =12