A cistern can be filled by a tap in 5 hours while it can be emptied by another tap in 10hours. If both the taps are opened simultaneously then after how much time will the cistern get filled?
Choose the correct choice from the following choices:  A) 20hr  B) 10hr  C) 5hr  D) 4hr  E) 15hr
Net part filled in 1 hour 1/5 - 1/10 = 1/10   The cistern will be filled in 10hr   Answer is 10hr
<result>B</result>
A cistern can be filled by a tap in 5 hours while it can be emptied by another tap in 10hours. If both the taps are opened simultaneously then after how much time will the cistern get filled?