Question

The radius of the Earth is approximately 3,960 miles. Find the approximate surface-area-to-volume ratio of the Earth.

Answer 1

B. 0.00076

Explanation:

Unit test on e2020

Answer 2

The surface area of a sphere is A = 4π R²

The volume of a sphere is V = (4/3) ( π) (R³)

The ratio of (surface area) to (volume) is

4 π R² / (4/3) (π) (R³)

Divide top and bottom by 4π : R² / (1/3) (R³)

Multiply top and bottom by 3: 3 R² / R³

Divide top and bottom by R² : 3 / R .

For the Earth,

A / V = (3) / (3,960 miles) = 0.00076 per mile (rounded)