Is it possible to assign different values to each zone. The value would be decimal.
If you have Spatial Analyst, you can use Reclassify tool to change the old pixel values to new values.
However, The tool may not work with decimals (I did not test it with decimals), but I know it works with integer values. You can try with decimals, if it did not work, then multiply the new values with 100 to make it integer.
For example, use
100 -> 497
(integer) instead of
100 -> 4.97
(decimal). Then using raster calculator divide the output by 100 to get the values in decimals.