it doesn't really matter much to me if it's "3" or "7", so if it comes out 9 times out of 10 as "3", I don't mind it, it's just to make things look a lil bit better to my professor, but it doesn't affect at all what I'm trying to achieve, so the time method works perfectly fine as well.

All I need this random for is because I'm finding the equation of a line between 2 points, and to do that, to find b in the y=mx+b formula, I can use either (x1, y1) or (x2, y2) and in my case 3 and 7 are actually point 1 and point 2, so either of them is fine, but thanks guys, all of you.

EDIT:
Things can be mixed, too. I can simply random between x & y, if the random is even I go for 3, if it's y I go for 7.