Multiple choice

A leak can empty a full tank in 12 minutes. If there is no leak, two pipes A and B can fill the tank separately in 15 minutes and 20 minutes respectively. If the leak is active and both the pipes are open, then the tank will be filled in -

  1. 22.5 min

  2. 25 min

  3. 27.5 min

  4. 30 min
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pipe A fills in 15 min (rate = 1/15 per min), Pipe B fills in 20 min (rate = 1/20 per min). Leak empties in 12 min (rate = 1/12 per min). Combined rate with leak = 1/15 + 1/20 - 1/12 = (4 + 3 - 5) / 60 = 2/60 = 1/30 per min. Time to fill = 30 minutes. Options A, B, C are common miscalculations without proper fraction addition.

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