The only people who know how the exams are scored are the people who designed the exams for Microsoft, and they aren't talking.
A passing score on the exam is 700 out of 1000 possible points. Unless each simulation counts for 301 points (and I have had exams with 4 or more simulations) then there's no way that would be true. Most people tend to think (or guess) that they count for more than a simple multiple choice question, but how much more nobody knows. Then of course there are the "choose 3 of 5" questions, which people also assume count for more than a simple "choose 1 of 4" style of question. Or the "drag and drop" type of exam questions where you have to drag the pieces of information to the correct parts of the diagram.
So basically just really prepare for the exam and get some hands on experience. You should do fine. Though I highly recommend registering for Second Shot before scheduling the exam, that way you'll get a free retake if you don't pass.
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CompTIA A+, Network+, Server+, Security+
MCSE:Security 2003
MCITP:Enterprise Administrator