Question

Two pipes A and B can fill a tank in 12 and 16 minutes respectively. Both the pipes are opened together but 4 minutes before the tank is full pipe A is closed in how many minutes the tank will totally fill?

• A. 9 minutes 8 seconds
• B. 10 minutes 9 seconds
• C. 11 minutes 19 seconds
• D. 11 minutes 29 seconds

Answer 1

Answer:

A. 9 minutes 8 seconds

Total quantity = lcm[12, 16] = 48 Efficieny of A = 48/12 = 4 Efficieny of B = 48/16 = 3 4 minutes before the tank is full pipe A is closed, So B alone is worked for 4 minutes Tank filled in 4 minutes = 4 × 3 =12 Remanining = 48 - 12 = 36 Work done by A + Work done by B = 36/7 = 5⅐ Total time = 4 + 5⅐ = 9⅐ = 9 minutes 1/7 × 60 seconds = 9 minutes 8 seconds