Formula for averaging grades dropping lowest grade?

I am setting up a grade book and would like to allow students to drop their lowest grade before averaging. How do I construct the formula?

I found the formula that would work, but I thought I'd post it here in case someone else is looking for the same thing.
Insert your own cell addresses and of course, the final number by which to divide, but this is the formula: =(SUM(B2:F2)-MIN(B2:F2))/4