Final answer:
To represent a 3 to 2 ratio with 5 boxes, 3 boxes should be shaded (denoted S) and 2 boxes should be unshaded (denoted U), such as in the arrangement S S S U U.
Step-by-step explanation:
To create a model using 5 boxes to represent a ratio of 3 to 2 of shaded to unshaded boxes, you need to have a total of five parts, three of which are shaded, and two of which are unshaded. Since there are 5 boxes, these parts can be directly translated into the boxes. For every 5 boxes, 3 should be shaded, and 2 should be unshaded. If we denote shaded boxes with 'S' and unshaded boxes with 'U', a possible representation could be S S S U U. This visually demonstrates the ratio where the first three boxes are shaded (to represent 3) and the last two are not (to represent 2).