The data shown in Table 3 measure crop yield for various amounts of fertilizer:

Solution (a) Figure 37 on page 22 shows the scatter plot. The data suggest the graph of a quadratic function.

(b) The graphing calculator screen in Figure 38 shows that the quadratic function of best fit is $$Y ( x) =-0.017x^{2}+1.0765x+3.8939$$ where $x$ represents the amount of fertilizer used and $Y$ represents crop yield. The graph of the quadratic model is illustrated in Figure 39.

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Figure 37

Figure 38

Figure 39