Subject: General Aptitude · Chapter: Volume and Surface Area · Exam: 2007 · Marks: · Difficulty:
If the radii of two spheres are in the ratio 1 : 4, then their surface areas are in the ratio
(a)1 : 2
(b)1 : 4
(c)1 : 8
(d)1 : 16
Answer
Answer (as printed): D
Explanation
Let the radii of the two spheres be $r$ and $4 r$ respectively. $$\text { Then, required ratio }=\frac{4 \pi r^{2}}{4 \pi(4 r)^{2}}=\frac{r^{2}}{16 r^{2}}=\frac{1}{16}=1: 16 .$$
Explanation as extracted from the printed page; notation may be imperfect.