Three pipes A, B and C can fill a tank from empty to full in 20 minutes, 20 minutes and 30 minutes respectively. When the tank is empty, all the three pipes are opened. A, B and C discharge chemical solutions P, Q and R respectively. What is the proportion of solution Q in the liquid in the tank after 3 minutes? Choose the correct answer:
A) 5/8
B) 6/8
C) 4/8
D) 2/8
E) 3/8
Part filled by (A + B + C) in 3 minutes = 3(1/20 + 1/20 + 1/30) = 6/15   Part filled by B in 3 minutes = 3/20   Required ratio = 3/20 * 15/6 =3/8   Answer:3/8
<result>E</result>
Three pipes A, B and C can fill a tank from empty to full in 20 minutes, 20 minutes and 30 minutes respectively. When the tank is empty, all the three pipes are opened. A, B and C discharge chemical solutions P, Q and R respectively. What is the proportion of solution Q in the liquid in the tank after 3 minutes?