Three pipes A, B and C can fill a tank in 30 min, 20 min and 10 min, respectively. When the tank is empty, all the three pipes are opened. If A, B and C discharge chemical solutions P, Q and R respectively, then the part of solution R in the liquid in the tank after 3 min is

A) \( \Large \frac{8}{11} \)

B) \( \Large \frac{5}{11} \)

C) \( \Large \frac{6}{11} \)

D) \( \Large \frac{7}{11} \)

Correct answer:
C) \( \Large \frac{6}{11} \)

Description for Correct answer:
Total quantity of solutions P, Q and R

from A, B and C respectively, after 3 min

= \( \Large \frac{3}{30}+\frac{3}{20}+\frac{3}{10}=3 \left(\frac{2+3+6}{60}\right) \)

= \( \Large \frac{3 \times 11}{60} = \frac{11}{20} \)

Quantity of solution R in liquid in 3 min = \( \Large \frac{3}{10} \)

Therefore, Part of solution R

= \( \Large \frac{10}{\frac{11}{20}} = \frac{3 \times 20}{10 \times 11} = \frac{6}{11} \)


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