I got 100% but I'm a little hesitant because a couple of the examples were a little ambiguous.
I've already done quals that I didn't follow up on because of "eeeeeehhhhh" moments in the HITs.
I would follow up with the requester and let them know your concerns. In order to get the qual, you needed to get 5 out of 6 right which is only 82% accuracy. Just let them know that you are a new worker, and you would like to do the hits, but are afraid of what would happen if they were to reject you.
In the hit, it says they monitor your work and will yank the qualification if you aren't meeting their standards. You can always do 50 or 100 and ask them to look them over.
Good communication goes a long way on both sides.