13.14 Calculate the linear correlation coefficient, r.

It is believed that the amount of nitrogen fertil- izer used per acre has a direct effect on the amount of wheat produced. The following data show the amount of nitrogen fertilizer used per test plot and the amount of wheat harvested per test plot. All test plots were the same size. [PT13-11] x, Pounds of Fertilizer y, 100 Pounds x, Pounds of Wheat of Fertilizer y, 100 Pounds of Wheat 30 9 70 19 30 11 70 22 30 14 70 31 50 12 90 29 50 14 90 33 50 23 90 35