ANSWER
307½ gallons of water
Step-by-step explanation
The volume of the rectangular swimming pool is
![V = l * w * h](https://img.qammunity.org/2020/formulas/mathematics/high-school/68edrhqsudm7h8dl7f27vy8u1q8eg83977.png)
where l=25ft and w=20½ ft.
when it is filled to a depth of 4½ ft ,then the height is , h=4½ ft.
We substitute these values into the formula to get:
![V = 25* 20.5* 4.5](https://img.qammunity.org/2020/formulas/mathematics/high-school/nm7p9i52ijfm0dvgyt8xe83je3yj41pwi0.png)
![V = 2306.25 {ft}^(3)](https://img.qammunity.org/2020/formulas/mathematics/high-school/aw8hty8sb9vumg2t80g53zxq1m77lodixm.png)
If one cubic foot of water is 7½ gallons, then 2306.25 cubic feet will be
![(2306.25)/(7.5) = 307.5gallons](https://img.qammunity.org/2020/formulas/mathematics/high-school/ez4pg8ot4wi8vkbvsyawmlichco7ibsnau.png)
We need 307.5 gallons of water to fill the pool.