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?  Select:
A) 6/11 B) 5/11 C) 7/11 D) 8/11 E) 9/11
Explanation:   Solution 1   Part of the tank filled by pipe A in 1 minute =1/30   Part of the tank filled by pipe B in 1 minute=1/20   Part of the tank filled by pipe C in 1 minute =1/10   Here we have to find the proportion of the solution R.   Pipe C discharges chemical solution R.   Part of the tank filled by pipe C in 3 minutes =3 X 1/10 = 3/10   Part of the tank filled by pipe A,B,C together in 1 minute =1/30 + 1/20 +1/10=11/60   Part of the tank filled by pipe A,B,C together in 3 minute =3 X 11/60 =11/20   Required proportion =(3/10) / (11/20)=3 X 20 / 10 X 11 = 6 /11.   6/11NSWER IS 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?