Multiple choice softskills communication

Pipe A can fill in 20 minutes and Pipe B in 30 mins and Pipe C can empty the same in 40 mins. If all of them work together, find the time taken to fill the tank ?

  1. 17 1/7 mins

  2. 20 mins

  3. 8 mins

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The combined rate is 1/20 + 1/30 - 1/40. Finding a common denominator (120), we get (6 + 4 - 3)/120 = 7/120. The time taken is the reciprocal, 120/7, which equals 17 1/7 minutes. The other options do not match the result of this rate calculation.

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