A swimming pool can be filled in 18 hours if water enters th

A swimming pool can be filled in 18 hours if water enters through a pipe alone, or in 25 hours if water enters through a hose alone. If water is entering through both the pipe and the hose, how long will it take to fill the pool five sixths full?

Solution

If water enters through a pipe alone, the swimming pool can be filled in 18 hours so 1/18th of the swimming pool can be filled in 1 hour if water enters through a pipe alone. Similarly, 1/25th of the swimming pool can be filled in 1 hour if water enters through a hose alone. Thus, if water enters through both the pipe and the hose , (1/18 + 1/25) = (25 +18)/(18*25) = 43/450th of the swimming pool can be filled in 1 hour. Therefore, if water enters through both the pipe and the hose, the swimming pool can be filled in 450/43 = 10.465 hours approximately ( on rounding off to 3 decimal places) or, 10 hours, 27 minutes, 54.42 seconds approximately.