A swimming pool holds 480000 liters of water The pool has tw

A swimming pool holds 480,000 liters of water. The pool has two drainage pipes. When the pool is completely full, the first pipe alone can empty it in 240 minutes, and the second pipe alone can empty it in 160 minutes. When both pipes are draining together, how long does it take them to empty the pool?

Solution

First pipe empty tank in 240min and second pipe 160 min alone

Both pipe will fill in = 1/(1/240 + 1/160)= 1/(5/480) = 480/5 min = 96 min