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?  Answers:
A) 5/11	B) 6/11	C) 7/11	D) 8/11	E) 9/11
PART filled (A+6/11+C) in 3 min = 3(1/30+1/20+1/10)=(3*11/60)=11/20   =&gt;3/10   req ratio = 6/11   ANSWER 6/11
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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?