A cistern can be filled by a tap in 4 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?
A. 4.5 hrs
B. 5 hrs
C. 6.5 hrs
D. 7.2 hrs
Answer:D
A cistern can be filled by a tap in 4 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?
A. 4.5 hrs B. 5 hrs C. 6.5 hrs D. 7.2 hrs