## Problem:

In a certain imaging study the screen is set to a scale of 1:3
(i.e. 1 cm viewed on the screen is equivalent to 3 cm in the
person’s body.) If a screen view of the liver displays a
lesion area of 1.6 cm2, how
large is the lesion area in the person’s liver?

## Solution:

You might say the solution is an easy ratio and proportion or
is it? The answer is not as simple as 3 x 1.6.

The trick is to recognize that when area is involved both
dimensions (length and width) are changing. If you visualize a
square 1 unit by 1 unit that expands to a square 3 units by 3
units, the area of the square increases by a factor of 9.

Or

The correct solution in this case is :