# Question #66f22

Mar 27, 2017

$x = 6 \times 3 = 18 k m$

#### Explanation:

Remember that a ratio - in this case, the scale, has no units.

But you can use any unit you like, as long as they are the same on each side.

In this case the given distance is in cm, so let's work with that.

$1 c m : 600 000 c m \text{ } \leftarrow$ convert this distance to km. ($\div 100 000$)

$1 c m : 6 k m \text{ } \leftarrow$ this form is much more useful and easier

$3 \times 1 c m : 3 \times 6 k m$

$3 c m : 18 k m$

You can also write a direct proportion:
(especially if the values are more difficult)

$\left(\text{map"rarr)/("reality} \rightarrow\right) = \frac{1 c m}{6 k m} = \frac{3 c m}{x k m}$

$x = 6 \times 3 = 18 k m$