Answer
See below
Work Step by Step
Given: $P(x)=0.0000984x^{4}-0.00712x^{3}+0.162x^{2}-1.11x+12.3$
The pineapple consumption is about $9.97$ pounds per person.
Then, we have the new equation: $9.97=0.0000984x^{4}-0.00712x^{3}+0.162x^{2}-1.11x+12.3$
Separate the left side and the right side of the equation:
$y=0.0000984x^{4}-0.00712x^{3}+0.162x^{2}-1.11x+12.3\\y=9.97$
The blue graph is the graph of $y=0.0000984x^{4}-0.00712x^{3}+0.162x^{2}-1.11x+12.3$. The red graph is the graph of $y=9.97$.