in a crowd of 90 people how many ways can 10 digital music p

in a crowd of 90 people how many ways can 10 digital music players be given away? counting principle, combination, factorial, permutation.
a computer randomly generate a 4 letter password. how many passwords are possible if letters may repeat? counting principles,combination, factorial, permutation.
in a sweepstakes with 90 entries, the selected winners each receive one of 10 big screen televisions. how many possible outcomes are there? counting principle, combination, factorial, permutation.

Solution

in a crowd of 90 people how many ways can 10 digital music players be given away?

permutation

as the first music player have 0 options, second has 89 and so on till 81 options.

a computer randomly generate a 4 letter password. how many passwords are possible if letters may repeat?

permutation.

as repitition allowed each of the four places have 26 options, so 26^4

in a sweepstakes with 90 entries, the selected winners each receive one of 10 big screen televisions. how many possible outcomes are there?

combination

basically choose 10 out of 90 entries. 90C10