Adding two array formulas

Hi,

I have a table that shows scores of questions in a test. Each question belongs to a subject, say "Physics", "Maths", etc. The scores can be 0 or 1.

Now I want to calculate the percentage correct in a given subject in one cell.
Normally, I would have made two named ranges for the subject and score cells, then used the array formula: sum((subject="Math")*(score)). However this only gives me the absolute score. Can I, in the same cell, calculate the proportion? I envision doing this by adding to the first array formula the following second array formula:
sum(subject="Math")

I'm using Excel 2013. Thanks!