Question

One tap can fill a water tank in 40 minutes and another tap can make the filled tank empty in 60 minutes. If both the taps are open, in how many hours will the empty tank be filled ?

• A. 2
• B. 2.5
• C. 3
• D. 3.5

Answer 1

Answer:

A. 2

Total work= LCM (40,60) = 120 Efficiency of the tap which fill the tank= 120/40 = 3 Efficiency of the tap which empty the tank= 120/-60 = -2 Total efficiency= 3 - 2 = 1 Time taken to fill the tank= 120/1 = 120 minutes = 2 hours