Question

If the diameter of a sphere is doubled, how does its surface area change?

• A. It increases two times
• B. It increases three times
• C. It increases four times
• D. It increases eight times

Answer 1

The correct option is D It increases eight times

If diameter is doubled, then radius is also doubled.
According to question, we have

$\frac{V_2}{V_1}=\frac{\frac{4}{3}\pi (2r{)}^3}{\frac{4}{3}\pi (r{)}^3}=\frac{8r^3}{r^3}=8$
$V_2=8V_1$