Multiple choice

A pipe can fill a tank with water in 3 hours. Due to leakage in bottom, it takes 3.5 hour to fill it. In what times the leak will empty the fully filled tank?

  1. 14

  2. 21

  3. 11

  4. 17

  5. 12
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Pipe fills 1/3 per hour. Pipe + Leak fills 1/3.5 = 2/7 per hour. Leak rate = 1/3 - 2/7 = (7-6)/21 = 1/21 per hour. The leak empties the tank in 21 hours.

AI explanation

Using the combined work formula, let the time it takes for the leak to empty the full tank be x hours. The equation is 1/3 - 1/x = 1/3.5. Converting the decimals to fractions gives 1/3 - 1/x = 2/7. Solving for the leak gives 1/x = 1/3 - 2/7 = 7/21 - 6/21 = 1/21, so the leak will empty the fully filled tank in 21 hours.

Keep practicing — related questions