A cistern is filled by pipe A in 20 hours and the full cistern can be leaked out by an exhaust pipe B in 25 hours. If both the pipes are opened, in what time the cistern is full?
Select the correct option: A) 50hrs B) 60hrs C) 70hrs D) 80hrs E) 100hrs
time taken to full the cistern=(1/20-1/25)hrs   =1/100   =100hrs   ANSW100hrsR:100hrs
<result>E</result>
A cistern is filled by pipe A in 20 hours and the full cistern can be leaked out by an exhaust pipe B in 25 hours. If both the pipes are opened, in what time the cistern is full?