4. An account password is 5 digits long. How many different passwords are possible if:

a) each digit is an upper case letter (A-Z) b) each digit is a number (0-9)

5. A recreational softball team has 12 players. a) The batting lineup has 9 players. How many different batting orders are possible?

b) They need 2 players to meet with the umpire at home plate. How many different groups of 2 are possible?

6. a) You have a loaded coin. The probability of heads is 0.55 and the probability of tails is 0.45. If you flip the coin 5 times, use the binomial probability formula to find the probability of getting exactly 3 tails.