If you are using the word diameter, I am going to assume that the pool is round. A round pool represents the shape of a cylinder. The volume for a cylinder is
![\pi r^2h](https://img.qammunity.org/2019/formulas/mathematics/middle-school/3wkqrh7fy55s9hldwf59typlacahj04u5l.png)
. Diameter is twice the radius, so our radius is half of 27 which is 13.5 feet. So our formula is
![V= \pi (13.5)^2(4)](https://img.qammunity.org/2019/formulas/mathematics/high-school/ym1vszlbz27nboj38kudgiyinb1dug1jll.png)
. That's the forumula for it. That actual volume measure is
![729 \pi ft^3](https://img.qammunity.org/2019/formulas/mathematics/high-school/9myl5uovfu327nc5uk745dv0yydoc9z1vf.png)
, or multiplying in pi as 3.14, it's 2289.06 cubic feet.