Answer
$15.7x^2=2252.8$
Work Step by Step
Given: $r=x\\h=5$
The total amount of water dispensed is $128(8.8)=1126.4$ cubic feet.
If the water dispensed makes the pool half full, then: $\frac{1}{2}V=1126.4\\\rightarrow V=2252.8$
The volume of a cylinder: $V=15.7x^2$
Substitute: $2252.8=15.7x^2$
Hence, the equation that can be used to find the radius is $15.7x^2=2252.8$
