Subject: General Aptitude · Chapter: Pipes and Cisterns · Exam: 2003 · Marks: · Difficulty:
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 solution R in the liquid in the tank after 3 minutes?
(a)$\frac{5}{11}$
(b)$\frac{6}{11}$
(c)$\frac{7}{11}$
(d)$\frac{8}{11}$
Answer
Answer (as printed): B
Explanation
Part filled by (A+B+C) in 3 minutes $= 3\left(\frac{1}{30}+\frac{1}{20}+\frac{1}{10}\right) = 3 \times \frac{11}{60} = \frac{11}{20}$. Part filled by C in 3 minutes $= \frac{3}{10}$. $\therefore$ Required ratio $= \frac{3}{10} \times \frac{20}{11} = \frac{6}{11}$.
Explanation as extracted from the printed page; notation may be imperfect.