A formula for an average grade generator

[sailor_taylor]

I am looking for a formula which will tell me the "missing grade (F1)" that will, when averaged with at least two other numbers (B1 - E1), will result in my goal of the number in cell A1.

Summary:

Cell A1 is the averaged grade I want to achieve

Cells B1, C1 (and sometimes D1 and E1) are known grades

Cell F1 is the number, when averaged with B1 - E1, will give me the grade in cell A1

This ugly formula works when there are two (and only two) known grades:

=(A1*3)-(B1+C1)

Any advice will be greatly appreciated.

 

[Andrew Poulsom]

Is it?

=(A1*COUNT(A1:E1))-SUM(B1:E1)

 

[West Man]

Working along the same line as your formula try:

=(A1*(COUNT(B1:E1)+1))-(Sum(B1:E1))

 

[sailor_taylor]

Thank you gentlemen for your prompt response. The formulas worked perfectly.