Subject: General Aptitude · Chapter: Volume and Surface Area · Exam: · Marks: · Difficulty:
The radius of a wire is decreased to one-third and its volume remains the same. The new length is how many times the original length?
(a)1 time
(b)3 times
(c)6 times
(d)9 times
Answer
Answer (as printed): D
Explanation
Let original radius $=r$ and original length $=h$. New radius $=\frac{r}{3}$ and let new length $=H$. Then, $$\pi r^{2} h=\pi\left(\frac{r}{3}\right)^{2} \times H \text { or } H=9 H \text {. }$$
Explanation as extracted from the printed page; notation may be imperfect.