Two hoses are pouring water into an empty pool. Hose 1 alone would fill up the pool in 6 hours. Hose 2 alone would fill up the pool in 7 hours. How long would it take for both hoses to fill up two-thirds of the pool?	Choices.
A) 5/12 hours B) 5/8 hours C) 28/13 hours D) 12/7 hours E) 12/5 hours
Hose 1 would fill the pool alone in 6 hours   i.e. 1 Hour work of Hose 1 = 1/6   Hose 2 would fill the pool alone in 7 hours   i.e. 1 Hour work of Hose 2 = 1/7   i.e. 1 Hour work of Hose1 and Hose2 together = (1/6)+(1/7) = (13/42)   i.e. (13/42) work can be finished by Hose1 and Hose2 together in 1 hour   i.e. (2/3) work can be finished by Hose1 and Hose2 together in 1*(42/13)*(2/3) = 28/13 hour   Answer: Option 28/13 hours
<result>C</result>
Two hoses are pouring water into an empty pool. Hose 1 alone would fill up the pool in 6 hours. Hose 2 alone would fill up the pool in 7 hours. How long would it take for both hoses to fill up two-thirds of the pool?