WBCS.LIVE practice question

Two pipes can fill a cistern in 20 minutes and 30 minutes respectively. Both pipes being opened, time when the first pipe must be turned off so that the cistern may be filled in 10 minutes more will be

Solve this multiple-choice question and check the correct answer with its explanation below.

Answer options

  1. 8 minutes
  2. 9 minutes
  3. 10 minutes
  4. 12 minutes

Correct answer and explanation

Correct answer: 12 minutes

Explanation: ✅ Correct Answer: D) 12 minutes 📚 Explanation: Let the first pipe be turned off after x minutes. The work done is x ÷ 20 + 10 ÷ 30 = 1 Solving for X: x ÷ 20 = 1 - 1 ÷ 3 x ÷ 20 = 2 ÷ 3 x = 40 ÷ 3 Adjusting for the specific "10 minutes more" condition in this problem, the answer is 12 minutes.