Conditional formulas that can be used in conditional formatting

[Linda-Decypher]

Help! Hopefully someone has the answer to this...

I have percentages that are meant to be evaluated, and then assigned a number from 1 to 3, and then each cell with a number is color coded according to the assigned number.
I can't figure out how to write the formula in conditional formatting to get the cells to change color correctly, can anyone help?

Example:

Rating 1 is assigned to 90% or higher, and the color of the cell needs to be green
Rating 2 is assigned to 80.0% through 89.99%, and the color of the cell needs to be yellow
Rating 3 is assigned to less than 80%, and the color of the cell needs to be red.

Each of the percentages is a calculated cell from other cell's data.

[Pete_UK]

... and then assigned a number from 1 to 3, and then each cell with a number is color coded according to the assigned number...

I don't understand this bit. If you already have a column where you have calculated the rating, then why not use that as the basis of the CF?

Hope this helps.

Pete