Three pipes A, B andC are attached to a tank. A and B can fill it in 20 and 30 minutes respectively while C can empty it in 15minutes. If A, B and C are kept open successively for 1 minute each how soonwill the tank be filled?

Three pipes A, B andC are attached to a tank. A and B can fill it in

1.	Three pipes A, B andC are attached to a tank. A and B can fill it in 20 and 30 minutes respectively while C can empty it in 15minutes. If A, B and C are kept open successively for 1 minute each how soonwill the tank be filled?
Answer» LCM of 15,20 and 30 is 60.so let the capacity of tank be 60 liters. A and B fill the tank at a rate of 3 liters per minute and 2 liters per minute. c empties the tank at a rate of 4 liters per minute. so if opened successfully for 1 minute each 1 liter will be filled in 3 minutes. so 55 liters will be filled in 55 x3=165 minutes , after the 165th minutetap A and B will fill 5 liters in 2 minutes. so total time taken =167 minutes = 2 hours and 47 minutes