BIO I= [2.3(4) + 2.3(4) + 3.7(4)]/ 12 = 2.766
Genetics= [2.3(3) + 3.3(3)]/9 = 2.8
That 9 should be a 6.
And when I go to calculate my cGPA I would use these numbers (2.766 and 2.8) added to the rest of my points:
for example: [2.766(4) + 2.8(3) + 30(4) + 18(2.7)]/(4+3+30+18) = 3.419
No, the above weighting isn't a GPA calc, nor does it do retakes correctly. It's neither AMCAS nor AACOMAS. You're using de-weighted averages as inputs, so it's not an average of grade points. Make those 4's 12's, make those 3's 6's.
And what's with that 30 and that 18? No idea what you're doing there.
[2.3(4) + 2.3(4) + 3.7(4) + 2.3(3) + 3.3(3) + 30(4)+ 18(2.7)]/(4+4+4+3+3+30+18) = 3.312
The bio & genetics grades are weighted correctly here for AMCAS, but the 30 and 18 don't make any sense. 4 units of a grade of 30? 30 units of a grade of 4? Why are you changing the order around?
Now, my question is whether my excel spread sheet is doing these calculations correctly (using the second method to give the 3.312 gpa)?
Own the math, don't blame Excel. Think it through. Don't use shortcuts if you're not getting consistent results.
You're not doing GPA calcs. A GPA calc looks like this:
[(course1grade*course1hours) + (course2grade*course2hours)... + (courseNgrade*courseNhours)] / (course1hours+course2hours...+courseNhours)
I have always thought that if you retake a course, the average grade is used (first method).
For AMCAS you average in all grades for all courses at one time, as my comment above. Don't pre-average and de-weight.
For AACOMAS you only include the highest grade. So your only bio input is 4 hours of 3.7, and your only genetics input is 3 hours of 3.3.
Note that if you have more than one school, or if you have semesters as well as quarters, you have to pick one standard for what "hours" means and convert the other hours. So if you took a 3 hour semester course for an A, and a 3 hour quarter course for a B, it would be [(4)(3) + (3)(2)] / (3+2), because a quarter system hour is two thirds of a semester system hour.
Best of luck to you.