If the radius of a circle is increased to 3 times, then how many times will its circumference be increased? · ABC26GN4654
Subject: General Aptitude · Chapter: Area
If the radius of a circle is increased to 3 times, then how many times will its circumference be increased?
(a)$\frac{1}{3}$ times
(b)2 times
(c)3 times
(d)9 times
Answer
Answer (as printed): C
Explanation
Let the original radius be $R$. New radius $=3 R$. Original circumference $=2 \pi R$. New circumference $$=2 \pi(3 R)=6 \pi R . \text { ∴ } \text { Required ratio }=\frac{6 \pi R}{2 \pi R}=3 .$$
Explanation as extracted from the printed page; notation may be imperfect.