Beetles in oats. In a study of leaf beetle damage on oats, researchers measured the number of beetle larvae per stem in small plots of oats after randomly applying one of two treatments: no pesticide or malathion at the rate of 0.25 pound per acre. Below are the summary statistics. Compute a 95% confidence interval for the difference in the mean number of beetle larvae per stem for the no pesticide group and malathion group.

Group Treatment Mean St. Dev n 1 no pesticide 3.47 1.21 13 2 malathion 1.36 0.52 14