A Cistern is filled by pipe A in 8 hrs and the full Cistern can be leaked out by an exhaust pipe B in 12 hrs. If both the pipes are opened in what time the Cistern is full? Choose the most appropriate option:
A) 12 hrs B) 24 hrs C) 16 hrs D) 32 hrs E) None of these
Explanation :   Pipe A can fill 1⁄8 of the cistern in 1 hour.   Pipe B can empty 1⁄12 of the cistern in 1 hour   Both Pipe A and B together can effectively fill 1⁄8-1⁄12= 1⁄24 of the cistern in 1 hour   i.e, the cistern will be full in 24 hrs. Answer : Option 24 hrs
<result>B</result>
A Cistern is filled by pipe A in 8 hrs and the full Cistern can be leaked out by an exhaust pipe B in 12 hrs. If both the pipes are opened in what time the Cistern is full?