What is the marginal average cost function?

Answer 1

It is meaningless.
There is an average cost function.
There is a marginal cost function.

combining them is meaningless.

Answer 2

That's interesting you say that, listed under my professor's list of things we need to study, he has that listed. Do you believe it to be a mistake? Should I email him perhaps? I see what you are saying here. Thank you Bob.

Answer 3

He might have meant

marginal/average cost function.

Email him at your own peril.