How many gallons of water do you need to fill a 15x30x4.5 feet pool?

The volume of a rectangular prism is given by the formula \(V=lwh\). In this case, the length is \(15\) feet, the width is \(30\) feet, and the height is \(4.5\) feet. So, the volume of the pool is:

$$V=(15)(30)(4.5)=2025 \text{ cubic feet}$$

There are \(7.48\) gallons of water in one cubic foot, so the number of gallons of water needed to fill the pool is:$$2025\times 7.48 = 15140 \text{ gallons}$$

Therefore, it would take approximately 15,140 gallons of water to fill the 15x30x4.5 feet pool.