How many gallons of water are needed to raise the level of a swimming pool 75' x 42' four inches above its present level?

( 1 cubic foot= 7 1/2 gallons )

75*42*(1/3) ft^3 * 7.5gal/ft^3 = 7875 gal

To find the number of gallons of water needed to raise the level of a swimming pool, you'll need to calculate the volume of water required.

First, you need to convert the dimensions of the pool into feet, as the conversion factor given is in cubic feet. The dimensions of the pool are 75 feet by 42 feet, and we need to raise the water level by 4 inches.

To convert the 4 inches to feet, divide it by 12 since there are 12 inches in a foot.

4 inches / 12 = 0.33 feet

Now, we can calculate the volume of water needed using the formula:

Volume = Length x Width x Height

Volume = 75 ft x 42 ft x 0.33 ft

Volume = 1042.5 cubic feet

Finally, we can convert the volume from cubic feet to gallons by multiplying it by the conversion factor given:

Volume in gallons = 1042.5 cubic feet x 7.5 gallons per cubic foot

Volume in gallons = 7818.75 gallons

Therefore, you would need approximately 7818.75 gallons of water to raise the level of the swimming pool 4 inches above its present level.