A cistern can be filled by a tap in 4 hours while it can be emptied by another tap in 8 hours. If both the taps are opened simultaneously, then after how much time will the cistern get filled?  Select the correct option:  A) 7.5  B) 7.4  C) 7.9  D) 7.2  E) 8.0
Net part filled in 1 hour = (1/4 - 1/9) = 1/8   The cistern will be filled in 8/1 hrs i.e., 8 hrs.Answer: 8.0
<result>E</result>
A cistern can be filled by a tap in 4 hours while it can be emptied by another tap in 8 hours. If both the taps are opened simultaneously, then after how much time will the cistern get filled?