(a) An automatic teller machine requires that each customer enter a four-digit personal identification number (PIN) when he or she inserts a bank card. If a person finds a bank card and guesses at a PIN to use the card fraudulently, what is the probability that the person will succeed in one attempt?
(b) If the person knows that the PIN will not have any digit repeated, what is the probability the person will succeed in guessing in one attempt?