posted by holly .
ok I get it, so once I get the prob figred for one person, how do I figure it if additional attempts are made and the question is about the prob of at least one of the additional attempts say n = 6 getting the same results as the first
Once you have the probability of passing the test with an >80% score happening once, call that P... It will be a very low number if t/f questions were guessed at random. The probability of not passing when trying once is 1-P (which is close to 1). . The probability of not passing after n independent attempts is (1-P)^n. The probability of passing after n attempts is
1 - (1-P)^n.