7.39 A field trial.

An agricultural field trial compares the yield of two varieties of tomatoes for commercial use. The researchers divide in half each of eight small plots of land in different locations and plant each tomato variety on one half of each plot. After harvest, they compare the yields in pounds per plant at each location. The eight differences (Variety A − Variety B) give the following statistics: and . Is there a difference between the yields of these two varieties? Write a summary paragraph to answer this question. Make sure to include , , and the -value with degrees of freedom.