Question

There are two pipes in a tank. If pipe A is opened the tank will be filled in 12 minutes ,and if pipe B is opened it will be filled in 20 minutes.If both are open together in how many minutes will it be filled ?

• A. 10 minutes
• B. 16 minutes
• C. 7½ minute
• D. 8 minutes

Answer 1

Answer:

C. 7½ minute

Total capacity of tank = LCM[12, 20] = 60 Efficiency of A = 60/12 = 5 Efficiency of B = 60/20 = 3 Efficiency of A + B = 5 + 3 = 8 Time taken by both pipes together = 60/8 = 7½ minute