Question

Water flows into a swimming pool at the rate of 8.0 gal/min. The pool is 16 ft wide, 32 ft long and 8.0 ft deep. How long does it take to fill in hours? (1 U.S. gallon = 231 cubic inches)

Answer 1

1 foot = 12 inches

(1 foot)^3 = (12 inches)^3

1 cubic foot = (12^3) cubic inches

1 cubic foot = 1728 cubic inches, will be used as a conversion factor

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Find the volume of the pool. Assume it is a rectangular prism.

Volume = length*width*height

Volume = 32*16*8

Volume = 4096 cubic feet

Multiply by 1728, which was the conversion factor found earlier, to convert from cubic feet to cubic inches.

4096 cubic feet = (4096*1728) cubic inches = 7077888 cubic inches

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Now use the fact that 1 gallon = 231 cubic inches to convert from cubic inches to gallons

7077888 cubic inches = (7077888 cubic inches)*(1 gallon/231 cubic inches) = 7077888/231 = 30640.2078 gallons which is approximate

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If x is the amount of time in minutes, then 8x gallons of water have been added after x minutes. Set this equal to 30640.2078 and solve for x

8x = 30640.2078

x = 30640.2078/8

x = 3830.02598

Divide this by 60 to convert to hours

3830.02598/60 = 63.8337663

It takes approximately 63.8 hours to fill the pool

This is approximately 63.8/24 = 2.625 days