Answer:
2.5 inches
Explanation:
To solve for the width, we can write a proportion comparing the original and reduced dimensions. Let w be the width of the model. So:

The left proportion represents the original length to width ratio. The right proportion represent the length to width ratio of the model. We can solve for w by cross multiplying.
First, let's reduce the fraction on the left:

Cross multiply:

Divide both sides by 2:

So, the width of the model is 2.5 inches.
And we're done!