At least one person on the interview team will push the candidate's limits to find the threshold of the candidate's experience. ("Find the cliff" - what the candidate doesn't know.) This kind of specific, obscure question seems to be one of those, signifying to me that this candidate probably was doing rather well in the interview. I was an engineer at Intel for almost 9 yrs. and never came across Baye's theorem, and I did have to use statistics. I'll have to make a Wiki run...