1. If one of your grades was math, you'll surely be able to find a formula for weighted averages, which is what I think you mean. Excel might have a function for it (see the help or the function wizard), but curiously enough when I use the help in my Excel (Dutch 97), I get some strange financial function when I choose 'weighted average' in the index, so I don't know. However, the empty's (for not yet finished grades) might present a difficulty for standard functions. Maybe sumif can be of use, combined with the isempty-function (when everything is filled, the sum-function seems to be handy).
2. The standard goal seeker varies 1 variable in a formula to find the goal. That might not be enough. So better load the Analysis Toolpak and study Linear Programming. That's a branch of mathematics to find optimal solutions for numeric problems when there are constraints (such a minimum and a maximum grade) and preferences (you might prefer a solution with a high grade for math and a low grade for history above the inverse one).
Hope this helps.
I have been trying to do a project that requires me to average my grades that have different percentages for each type of project. I also need to do a what if formula and a goal seeking formula for grades not yet made. How do you tell Excel to figure say a grade that is 2% of total grade and you made a 95. Then you would have to tie all percent sums together and total at bottom with If formulas and goal seeking formulas in spots where 0s are present on grades not yet finished.