Set an Excel cell's color based on multiple other cells' colors

I have an Excel 2007 spreadsheet for a list of products and a bunch of factors to rate each one on, and I'm using Conditional Formatting to set the color of the cells in the individual attribute columns. It looks something like this:

I want to fill in the rating column for each item with a color, based on the color ratings of its individual attributes. Examples of ways to determine this:

• the color of the category in which the item scored worst


• the statistical mode of the category colors


• the average of the category ratings, where each color is assigned a numerical value

How can I implement any or all of the above rules? (I'm really just asking for a quick overview of the relevant Excel feature; I don't need step-by-step instructions for each rule.)

EDIT:
Sample current rules: