I can buy that Ash is intelligent but lazy... In other words he chooses not to use it and is happy to coast through life in blissful ignorance.
Mark though...
... That's verging on literally retarded (under 80).
Then again, they probably used the quick "pop quiz" IQ tests you get online, not a full on mensa test. So the results are questionable in absolute terms. They should still be accurate for "ranking" though, I suppose.