Multiple choice

Two pipes A and B can fill a tank in 12 minutes working together. If pipe A can fill the tank in 20 minutes, the time taken to fill the tank by B is -

  1. 25 minutes

  2. 18 minutes

  3. 30 minutes

  4. 40 minutes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Combined rate: 1/12 tank per minute. A's rate: 1/20 per minute. B's rate = Combined - A = 1/12 - 1/20 = (5-3)/60 = 2/60 = 1/30. Therefore, B alone takes 30 minutes.

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