Is mixing two colors of paint a physical or chemical change?

It depends on the paint. It's not impossible that the pigments in the paints might react chemically. However, it's more likely that they won't, and it will simply be a physical change.

If this came from a textbook, the authors should be smacked with a wet fish; anyone writing a book about chemistry should know better than to ask a question like this.

it is a physical change because when you try to the mix the paint it doesn't make a totally new substance OK