A water tank is two-fifth full.Pipe A can fill a tank in 10 minutes and pipe B can empty it in 6 minutes.If both the pipes are open,how long will it take to empty or fill the tank completely?
Choose the correct choice from the following options
A) 6 min.to empty	B) 9 min.to empty	C) 5 min.to empty	D) 4 min.to empty	E) 7 min.to empty
Explanation:   Clearly,pipe B is faster than pipe A and so,the tank will be emptied.   part to be emptied = 2/5   part emptied by (6 min.to empty+B) in 1 minute=   so, the tank will be emptied in 6 min   6 min.to emptynswer: 6 min.to empty
<result>A</result>
A water tank is two-fifth full.Pipe A can fill a tank in 10 minutes and pipe B can empty it in 6 minutes.If both the pipes are open,how long will it take to empty or fill the tank completely?