Question: 2 pipes can fill a tank in 6 hours?
Answer: Two pipes, A and B, can fill a tank in 6 hours and 4 hours respectively. If they are opened on alternate hours and if pipe A is opened first, in how many hours will the tank be full? The pipe A fills a tank in 6 hours and pipe B fills it in 4 hrs. fill 1/6+1/4=5/12 of the tank.