Question

The diameter of a basketball is 4 times the diameter of a tennis ball. Then, the ratio of the surface area of the basketball to that of the tennis ball is _____.

• A.
  $16:1$
• B.
  $1:16$
• C.
  $8:1$
• D.
  $1:8$

Answer 1

The correct option is A

$16:1$
Let the diameter of the tennis ball be $d$.
Then, the diameter of the basketball ball is $4d$.

We know that the surface area of a sphere $=4\pi r^2$

Now,
required ratio $=\frac{\text{Surface area of the basketball}}{\text{Surface area of the tennis ball}}$
$=\frac{4\pi (\frac{4d}{2}{)}^2}{4\pi (\frac{d}{2}{)}^2}$
$=\frac{16}{1}$
$=16:1$