A cistern is filled by pipe A in 8 hours and the full cistern can be leaked out by an exhaust pipe B in 12 hours. If both the pipes are opened, in what time the cistern is full?
Choose the correct answer:
A) 24hrs
B) 60hrs
C) 70hrs
D) 80hrs
E) 90hrs
time taken to full the cistern=(1/8-1/12)hrs   =1/24   =24hrs   24hrsNSWER:24hrs
<result>A</result>
A cistern is filled by pipe A in 8 hours and the full cistern can be leaked out by an exhaust pipe B in 12 hours. If both the pipes are opened, in what time the cistern is full?