Two pipes A and B can fill a cistern in 12 minutes and 16 minutes respectively. If both the pipes are opened together, then after how much time B should be closed so that the tank is full in 9 minutes ?
A. 3 min and 30 sec.
B. 4 min and 30 sec.
C. 4 min.
D. 4 min 77 sec.
Answer:C
Two pipes A and B can fill a cistern in 12 minutes and 16 minutes respectively. If both the pipes are opened together, then after how much time B should be closed so that the tank is full in 9 minutes ?
A. 3 min and 30 sec. B. 4 min and 30 sec. C. 4 min. D. 4 min 77 sec.
Explanation: A tank can be filled by a tap in 20 minutes and by another tap in 6O minutesLet B be closed after x minutes. Then,