5 My credit card has a 4-digit code called a PIN. You should assume that any 4-digit number from 0000 to 9999 can be a PIN.
- If I cannot remember any digits and guess my number, find the probability that I guess it correctly.
In fact my PIN consists of four different digits. I can remember all four digits, but cannot remember the correct order.
- If I now guess my number, find the probability that I guess it correctly.