Help me with this simple geometry question please?

Question

A water pipe with an inside diameter of 1/2 inches is 60 feet long in its run from the hot-water tank to the faucet. How much hot water is wasted when the water inside the pipe cools down. Give your answer in gallons where 1 gallon=231 in^3. Use Pi=3.1416 

Answer 1

A water pipe diameter(d) = 1/2 inches

Radius of water pipe(r) = d/2 = 1/4 = 0.25 inches.

Water pipe is 60 feet long.

1 ft = 12 inches.

60 ft = 60*12 inches = 720 inches

h = 720 inches, r = 0.25 , pi = 3.1416

Volume of the empty water pipe

To find how many gallons of water is wasted just divide the volume/231in^3.

0.612 gallons hot water is wasted when the water inside the pipe cools down.