Question

If the radius of a sphere is doubled, then what is the ratio of new to the old surface area?

• A. $1:2$
• B. $2:1$
• C. $1:4$
• D. $4:1$

Answer 1

Answer: (D)

$4:1$

$S_1=4\pi r^2{S}_2=4\pi (2r{)}^2=16\pi r^2\frac{S_2}{S_1}=\frac{16\pi r^2}{4\pi r^2}=\frac{4}{1}\Rightarrow 4:1$