how many gallons of water can fill a pool that is 50 yards by 20 yards and is 9 feet deep (assume 7 1/2 gallons per square foot)

Assume:

7.5 (US)gallons / cubic foot

Volume of pool
=(50*3')*(20*3')*9'
=81000 cubic feet

Multiply pool volume by 7.5 (US)gal./cubic foot gives the total capacity of the pool.

To find the number of gallons of water that can fill a pool, you need to calculate the volume of the pool first.

The volume of a rectangular pool can be calculated by multiplying its length, width, and depth.
Given:
Length of pool = 50 yards
Width of pool = 20 yards
Depth of pool = 9 feet

First, let's convert the measurements to the same units:
1 yard = 3 feet
So, 50 yards = 50 * 3 = 150 feet
And, 20 yards = 20 * 3 = 60 feet

Volume of the pool = Length * Width * Depth
Volume of the pool = 150 feet * 60 feet * 9 feet

Now, let's convert the volume to gallons. Given that there are 7 1/2 gallons per square foot.

Volume in cubic feet * 7.5 = Volume in gallons
(Volume of the pool) * 7.5 = (150 feet * 60 feet * 9 feet) * 7.5

Calculate the volume in gallons:
Volume in gallons = (150 * 60 * 9 * 7.5) cubic feet

Therefore, the pool can hold (150 * 60 * 9 * 7.5) gallons of water.