An inlet pipe can fill an empty tank in 140 hours while an outlet pipe drains a completely-filled tank in 63 hours. If 8 inlet pipes and y outlet pipes are opened simultaneously, when the tank is empty, then the tank gets completely filled in 105 hours. Find the value of y.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 3
Given:
An inlet pipe can fill an empty tank in 140 hours
An outlet pipe drains a completely-filled tank in 63 hours
The tank gets completely filled in 105 hours
Concept Used:
Total work = Efficiency × Time
Explanation:
Let the total capacity of the tank be LCM (140, 63) = 1260 units
The efficiency of the inlet pipe to fill the tank (1260/140) = 9
The efficiency of the outlet pipe to empty the tank (1260/63) = 20
The tank gets completely filled in 105 hours.
According to the question
⇒ 8 × 9 - 20 y = 1260/105
⇒ 72 - 20 y = 12
⇒ 20y = 72 - 12
⇒ 20 y = 60
⇒ y = 60/20
⇒ y = 3