The ratio of the rate of flow of water in pipes varies inversely as the square of the radius of the pipes… · ABC26GN3149
Subject: General Aptitude · Chapter: Ratio and Proportion · Exam: M.A.T. 2005
The ratio of the rate of flow of water in pipes varies inversely as the square of the radius of the pipes. What is the ratio of the rates of flow in two pipes of diameters 2 cm and 4 cm?
(a)1 : 2
(b)2 : 1
(c)4 : 1
(d)1 : 8
Answer
Answer (as printed): C
Explanation
Rate of flow $\alpha \frac{1}{r^{2}} \Rightarrow$ Rate of flow $$=\frac{k}{r^{2}} \text { for some constant } k .$$ ∴ Required ratio $=\frac{k}{1^{2}}: \frac{k}{2^{2}}=\frac{k}{1}: \frac{k}{4}=1: \frac{1}{4}=4: 1$.
Explanation as extracted from the printed page; notation may be imperfect.