Conditional formatting in Excel for Mac

Hi - I am running Microsoft Excel for Mac 2011 and want to conditionally format an array of cells based on the text contained in another cell. For example:

Cell O1 contains a drop down list and depending on the text displayed I would like the array of O4:R15 to change colour. When "Proposed Price $" is displayed I would like the cells to be red and when "Agreed Price $" is displayed I would like the cells to be green. Note that the cells in the array contain other values or formulas.

Does anyone know if it possible to do this? If so, how? Thanks in advance!