We have gone through a plethora of, quite frankly, nonsense concerning the knowledge that is appropriate for, and required of private pilots. Both JAA and EASA and have imposed requirements that have no vocational or academic validity, and erstwhile arguments have been proffered, by amongst other AOPA, that have essentially had us going around in circles so that we end up back to where we were in the 1980s. The same can be said of the professional examinations; trained chimps could pass them, and in the world of academia pass marks of 85-90% are unheard of. MJ mentions this stuff being available on the net - no surprise there. Beagle alludes to the FAA Oral; If you have been through that you know you need to, and know your stuff. Focusing just now on the PPL exams, there is a huge amount of talent and guts on here to make a difference. If the exams lack credibility, don't be surprised if they are treated accordingly and the pass rate might be very high!!