Help with a GPA formula

[Bogazetti]

I need a formula to translate a letter grade into the equivalent number, and
then averaging that to find the grade point average of students. So, like an
A would = 4.00, A-=3.67 and so on. I want to be able to type in the letter
grades and have it changed to the correct number and then averaged.
Thanks in advance

 

[Jim Thomlinson]

2 best solutions would be to use Index / Match or Vlookup

Place a table in cells A1:B8 that looks like this...
A 4
A- 3.675
B+ 3.35
B 3.025
C+ 2.7
C 2.375
D 2.05
E 0

then use a formula such as this
=INDEX($B$1:$B$8, MATCH(D1, $A$1:$A$8, 0))
or
=VLOOKUP(D1, $A$1:$B$8, 2, 0)

Where the value you are trying to look up is in cell D1. My preference is
the index and match formula but they both work...