I'm still struggling a bit with putting a lot of things in the same function,
so I'm looking for a little help on the following problem:

Column B contains a lab result value; Column D contains a Pass/Fail value.
I'm trying to calculate a pass/fail percentage for specific ranges of the lab
result (i.e. APC<=500, 500<APC<=1000). The way I want the formula to run is

(APC<=500 and NOT(ISNA(PassFail)) and PassFail=1)/(PassFail=1 +
PassFail=0)

If that makes sense, please help me out. If not, let me know and I'll try
and put down more concisely what I want.