I think their are actually 50 RC questions so that max score of 17 is for one of the 3 passages. Therefore there are 16.66 (50 divided by 3) questions in each passage... then it makes more sense that a 17/17 for one passage would be a score of 29. One passage may have 15 questions and another may have 18 so this way of self scoring is just an estimate. Hope that clears it up a bit.