Pipes A and B can fill a tank in 16 hours and 24 hours, respectively, whereas pipe C can empty the full tank in 40 hours. All three pipes are opened together, but pipe C is closed after 10 hours. After how many hours will the remaining part of the tank be filled?
Answer & explanation
Correct answer: option 2
Capacity of the tank = LCM of 16, 24, 40
Total efficiency of the system = 15 + 10 - 6 = 19
Capacity of the tank filled in 10 hrs = time x efficiency
= 10 x 19 = 190
Capacity of the tank after this = 240 - 190 = 50
This will be filled by A and B in $\frac{50}{eff.\;of\;A\;+\;B}$
= $\frac{50}{25}$ = 2hrs