Two pipes A and B can fill a cistern in 12 min and 16 min respectively. Both the pipes are opened together for a certain time but due to some obstruction the flow of water was restricted to 7878 of full flow in pipe A and 5656 of full in pipe B. This obstruction is removed after some time and tank is now filled in 3 min from that moment. How long was it before the full flow.

Two pipes A and B can fill a cistern in 12 min and 16 min respectively

1.	Two pipes A and B can fill a cistern in 12 min and 16 min respectively. Both the pipes are opened together for a certain time but due to some obstruction the flow of water was restricted to 7878 of full flow in pipe A and 5656 of full in pipe B. This obstruction is removed after some time and tank is now filled in 3 min from that moment. How long was it before the full flow.
A.	8 min
B.	3 min
C.	5.6 min
D.	4.5 min
Answer» B. 3 min