Multiple choice

Three pipes A, B and C can fill an empty tank in 15, 10 and 5 minutes respectively. When the tank is empty, all three pipes are opened simultaneously. A chemical solution P comes out of A. What is the amount of solution P in the tank after 2 minutes?

  1. 9/11

  2. 12/11

  3. 6/11

  4. 2/11

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pipe rates: A = 1/15 per min, B = 1/10 per min, C = 1/5 per min. Combined rate = 1/15 + 1/10 + 1/5 = 11/30 per min. In 2 minutes, tank fills to 22/30 = 11/15. Pipe A contributes 2/15 of solution P. Proportion of P = (2/15)/(11/15) = 2/11 of the total solution in the tank.