I used to get 16-17 on CDP and that's what i got on real test. So, I would say it's on the spot.. Work harder..
lol jk.. I am averaging about 16-17 on it. It's not even worth practicing those questions. It has reactions that I have never even read before. So, don't worry abt it.
Just practice for fun but don't expect to score more than 18 on it.. If you score abt 17-18 then I would say you are good to go..