djs25uk,
Attached is an example workbook based on the sample criteria provided. I used a table to assign each Letter Grade with a Numeric Value. Named that table GradeVals.
Using that table, I was able to add a helper column to that contains a vlookup formula to determine if the row should be red, blue, or left alone:
=IF(VLOOKUP(C6,GradeVals,2,FALSE)>=VLOOKUP(B6,GradeVals,2,FALSE),"red",IF(VLOOKUP(C6,GradeVals,2,FALSE)<=VLOOKUP(B6,GradeVals,2,FALSE)+2,"blue",""))
Once the helper column formula was copied down, the conditional formatting and countif formulas were easy.
Hope that helps,
~tigeravatar
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