In: Statistics and Probability
A certain website wants you to build a 6-character password from the letters a through i, the numbers 0 − 9, or the symbols @, #, or &. Clearly, the order of the characters in the password matters
(a) How many passwords are there in total?
(b) How many passwords are there that consist of distinct characters?
(c) How many passwords have the first two characters be letters, the middle two character be one of the symbols and the last two characters be numbers where each character does not have to be distinct?