Multiple choice

Pipe A can fill a tank in $5$ hours, pipe B in $10$ hours and pipe C in $30$ hours. If all the pipes are open, in how many hours will the tank be filled?

  1. $3$ hrs
  2. $2$ hrs
  3. $2.5$ hrs
  4. $3.5$ hrs
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rates: A=1/5, B=1/10, C=1/30. Combined rate = 1/5 + 1/10 + 1/30 = (6+3+1)/30 = 10/30 = 1/3. Time = 1 / (1/3) = 3 hours.

AI explanation

Using the combined work formula, the hourly rates for pipes A, B, and C are 1/5, 1/10, and 1/30 respectively. Adding these gives 6/30 + 3/30 + 1/30 = 10/30 = 1/3 of the tank per hour. The total time to fill the tank is the reciprocal of this rate, which is 3 hours.

Keep practicing — related questions