# The diameter of Earth, about 8,000 miles, is about 4 times the diameter of the moon. What is the approximate diameter of the moon?

Nov 13, 2016

The diameter of the moon is approximately 2,000 miles.

#### Explanation:

First, because we are solving for the approximate diameter of the moon, let's call the variable representing the diameter of the moon $m$.

And let's call the diameter of the Earth $e$.

The problem provides the relationship of the diameter of the Earth compared to the diameter of the moon. If equation for it can be written as:

$e = 4 \times m$

Because the diameter of the Earth ($e = 8000$) is provided we can substitute this into the formula and then solve for the approximate diameter for the moon which we called $m$ while keeping the equation balanced.

$8000 = 4 \times m$

$\frac{8000}{4} = \frac{4 \times m}{4}$

$2000 = \left(\frac{4}{4}\right) \times m$

$2000 = 1 \times m$

$m = 2000$