A tanker has two inlets which fill it in 12 min. and 15 min. respectively. There is also a outlet pipe and when all the three are opened, the empty tanker becomes full in 20 min. How long will the waste pipe take to empty the full tank ?
Solution: Formula: If a pipe can fill a tank in x hours and another pipe can empty the full tank in y hours, then on opening both the pipes, the net part filled in 1 hour = (1/x - 1/y) (where y > x).
=> 1/x = (1/12 + 1/15) - 1/20 = 3/20 -1/20 = 2/10 = 1/10.
=> waste pipe empty the full tank in 10 min.
Back To Top