An inlet pipe can fill an empty tank in 3.6 hours, while an outlet pipe can drain a completely-filled tank in 6.3 hours. If both the pipes are opened simultaneously when the tank is empty, in how many hours will the tank get completely filled?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 8.4.
Given:
An inlet pipe can fill an empty tank in 3.6 hours
An outlet pipe can drain a completely-filled tank in 6.3 hours
Concept Used:
Total work = Efficiency × Time
Explanation:
Let the total capacity of the tank be LCM (3.6, 6.3) = 25.2 units
The efficiency of the inlet pipe = 25.2/3.6 = 7
The efficiency of the outlet pipe = 25.2/6.3 = 4
The combined efficiency of both pipes together = 7 - 4 = 3
Hence, the tank will get completely filled with both pipes together = 25.2/3 = 8.4 hours