This problem is not as simple as it may appear at first. The area of an ellipse is ...
... A = πab
where <em>a</em> and <em>b</em> are the semi-axes.
Here, it looks like you're expected to choose these to be 1.5 ft longer than half the given axes, so the area of the pool cover is about ...
... A = π(9 ft + 1.5 ft)(12.5 ft +1.5 ft)
... A = 147π ft² ≈ 461.8 ft²
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However, adding 1.5 ft of material to an ellipse results in a shape that is <em>not an ellipse</em>, but is slightly larger than the ellipse with the dimensions used above. The area of that may be about 462.5 ft² (found numerically).