To Investigate the Relationship Between Yield of Potatoes, Y, and Level

To investigate the relationship between yield of potatoes, y, and level of fertilizer
application, x, a researcher divides a field into eight plots of equal size and applies
differing amounts of fertilizer to each. The yield of potatoes (in pounds)and the fertilizer
application (in pounds)are recorded for each plot. The data are as follows: $\begin{array}{l|cccccccc}\hline x & 1 & 1.5 & 2 & 2.5 & 3 & 3.5 & 4 & 4.5 \\\hline y & 25 & 31 & 27 & 28 & 36 & 35 & 32 & 34 \\\hline\end{array}$

Summary statistics yield $S S _ { x x } = 10.5 , S S _ { y y } = 112 , S S _ { x y } = 25$ , and $S S E = 52.476$ . Calculate the coefficient of correlation.