Originally Posted by Da40Pilot

I think this is as close I will get to what may be a correct answer. I remember the RAIM or GPS needs to be accurate to 0.3NM at the FAWP, and that the interrogation is continuous. I also pulled up AC 90-100A which states, as CLT Guy mentioned above that RNAV requires a total system error of not mor than 1NM for 95% of the flight time.

Not sure why they're asking this question either, but, rather be safe than sorry, every question missed is worth 4% for that 80% passing score.