Conditional Formatting Colors Based on Max Values

Hi All,

I have three cells: [A1], [A2] and [A3]. Each one has a random number which is generated every few seconds automatically by a real-time feed. How do I format so that in [A5] I get an associated color based on where that number is coming from? For example, my formula in [A5] is max(a1,a2,a3). I want A5 to light up in yellow if the value is coming from A1, blue if it is coming from A2 and red if it is coming from a3. I also want to be able to copy and paste this formula to the right and keep the same syntax... for example b5 = max(b1, b2, b3) and the conditional formatting is based on b1, b2, b3.

Thanks guys!

Larry