An electric pump can fill a tank in 4 hours. Because of a leak in the tank, it took 4½ hours to fill the tank. If the tank is full, how much time will the leak take to empty it?

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  1. 48 hours
  2. 21 hours
  3. 36  hours
  4. 18  hours

Answer (Detailed Solution Below)

Option 3 : 36  hours
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Detailed Solution

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Given:

An electric pump can fill a tank in 4 hours.

A leak in the tank, it took  hours to fill the tank. 

Calculation:

Net, time taken by the leakage to empty a completely filled tank = t hours

According to the question,

1/4 - 1/t = 2/9

⇒ 1/t = 1/4 - 2/9

⇒ 1/t = (9 - 8)/36

⇒ 1/t = 1/36

⇒ t = 36 hours

∴ In 36 hours the leakage will empty a completely filled tank.

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