One pipe can fill a pool four times faster than a second pipe. When both pipes are opened, they fill the pool in eight hours. How long would it take to fill the pool if only the faster pipe is used?
Choose the correct choice from the following options:	A) 5 hr	B) 8 hr	C) 10 hr	D) 16 hr	E) 20 hr
fast pipe + slow pipe = together   One pipe fills the pool four times faster than the other pipe so,   hourly fill rates:   1/x + 1/4x = 1/8   Let x = number of hours it would take the fast pipe to fill the pool thus,   x=10 hours   Answer: 10 hr
<result>C</result>
One pipe can fill a pool four times faster than a second pipe. When both pipes are opened, they fill the pool in eight hours. How long would it take to fill the pool if only the faster pipe is used?