Leo Heuser answered a similar question in Feb 2004 with the following...
(I was impressed enough with it to retain it in my code library)
Jim Cone
San Francisco, USA
'--------------------------
Averaging letter grades
"I'd like to know if it is possible to write a formula that will average 16
letter grades in column b, from row 6 to 21 is where i enter the letter grade
for each assignment. I'd like to have the average of these grades in g23."

If "+" and "-" are included, here's one
way to do it. Remove and add elements
if necessary. All numbers are rounded to
nearest integer. E.g. an average of 7.8125
will round to 8, which is C.
(F- is 1 and A+ is 15)

In G23 enter:

=INDEX({"F-","F","F+","D-","D","D+","C-","C","C+","B-","B","B+",
A-,"A","A+"},ROUND(AVERAGE(MATCH(B6:B21,{"F-","F","F+",
D-,"D","D+","C-","C","C+","B-","B","B+","A-","A","A+"},0)),0))

The formula is an array formula, and
must be entered with <Shift<Ctrl<Enter
also if edited later.
'--------------------------


"billynolan"

wrote in message

I need to calculate the average student grades on student profile sheets. for
example a student might recieve grades A, A, B, B, A - how do I get excell to
display A as the average grade?