Three pipes A, B and C can fill a tank from empty to full in 30 minutes, 20 minutes, and 10 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 the solution R in the liquid in the tank after 3 minutes?	Options:
A) 6/11
B) 6/13
C) 6/15
D) 7/11
E) 7/13
Part filled by (A + B + C) in 3 minutes = 3 1	+	1	+	1 = 3 x	11 =	11	.   30	20	10	60	20   Part filled by C in 3 minutes =	3	.   10   Required ratio = 3/10	x	20/11 =	6/11	.   6/11nswer 6/11)
<result>A</result>
Three pipes A, B and C can fill a tank from empty to full in 30 minutes, 20 minutes, and 10 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 the solution R in the liquid in the tank after 3 minutes?