An experiment was conducted to evaluate the effectiveness of a treatment for tapeworm in the stomachs of sheep. A random sample of 24 worm-infected lambs of approximately the same age and health was randomly divided into two groups. Twelve of the lambs were injected with the drug and the remaining twelve were left untreated. After a 6-month period, the lambs were slaughtered and the following worm counts were recorded. Drug-Treated Sheep 18 43 28 50 16 32 13 35 38 33 6 7
Untreated Sheep 40 54 26 63 21 37 39 23 48 58 28 39
Test whether the mean number of tapeworms in the stomachs of treated lambs is less than the mean for untreated lambs. Use a=.05.