Suppose that you are planning a study in which you will measure the diameters of longleaf pine trees in two tracts of land. You are willing to assume that the standard deviation for both tracts is 20 cm. Suppose that a difference in mean DBH (diameter at breast height) of 10 cm or more would be important to detect. You will use a t statistic and a two-sided alternative for the comparison. Find the power if you randomly sample 60 trees from each area to be compared. Assume a significance level of 5%