US History Part I: How well do you need to know the IC cards to pass??

[KJArsenal]

My son is taking his first CLEP in two weeks: US History Part I. We have been all over these boards (including the test specific boards=awesome!). He is working on the IC cards everyday and is making steady progress. We wondering how well you need to know the cards to pass the test though? Should you be getting 90%+ on each set of cards?? Or will a 75% on the set be sufficient? We are worried he won't have them memorized 100% by the time the test occurs....

Thanks!
KJ