4 digit PIN number - please help
I am stuck with this puzzle
I have forgotten my 4 digit PIN number
However, I can remember the following facts:
the first and last digits add up to 10
the first digit is greater than the last digit
the four digits add up to 16
the difference between the last two is 2
Make a list of the 7 possible numbers which fit the facts above.
What is the probability that the 4 digit number had two digits the same?
What is the probability that it is not the correct PIN Number?