You sure? I'm pretty sure it's AND. For example, xenforo.com has a trophy for having X messages and X likes (I'm assuming they didn't do anything custom for that). I also did a mini test on that a long time ago and I wasn't able to get the trophy without satisfying both requirements. I don't remember if I disabled all addons when testing though.
Not sure if they would use a ratio for that because technically someone who only has 10 likes and 5 posts would also obtain the same trophy, I think... I just did a quick test, and yea I wasn't able to get a trophy unless I satisfied all requirements. It would also not be too useful IMO if it was OR instead of AND.