A cistern can be filled by a tap in 5 hours while it can be emptied by another tap in 9 hours. If both the taps are opened simultaneously, then after how much time will the cistern get filled ?	Choose the correct choice from the following:
A) 4.5 hrs	B) 5 hrs	C) 6.5 hrs	D) 7.25 hrs	E) 11.25 hrs
Net part filled in 1 hour= 1/5 -1/9= 4/45   Therefore the cistern will be filled in 45/4 hours or 11.25 hours.   ANSW11.25 hrsR:11.25 hrs
<result>E</result>
A cistern can be filled by a tap in 5 hours while it can be emptied by another tap in 9 hours. If both the taps are opened simultaneously, then after how much time will the cistern get filled ?