Question

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?

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

Part filled by (A+B+C) in 3 minutes
$=3(\frac{1}{30}+\frac{1}{20}+\frac{1}{20})=(3\times \frac{11}{60})=\frac{11}{20}$
Part filled by C in 3 minutes$=\frac{3}{10}$
$\therefore$ Required ratio$=(\frac{3}{10}\times \frac{20}{11})=\frac{6}{11}$