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 P in the liquid in the tank after 3 minutes? Choose one.
A) 3/8	B) 2/8	C) 6/7	D) 3/5	E) 2/5
Part filled by (3/8 + B + C) in 3 minutes = 3(1/20 + 1/20 + 1/30) = 6/15   Part filled by 3/8 in 3 minutes = 3/20   Required ratio = 3/20 * 15/6 =3/8   3/8nswer:3/8
<result>A</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 P in the liquid in the tank after 3 minutes?