a. c. Suppose all passcodes have 10 characters made from uppercase letters, digits, and 10 symbols. Suppose a computer generates a passcode at random. What is the probability the passcode contains exactly 7 letters? b. What is the probability the passcode contains at least 3 letters? What is the probability the passcode contains fewer than 3 letters? d. What is the probability the passcode has 5 letters followed by 5 nonletters? What is the probability the passcode alternates letter, nonletter, and begins with a letter? f. What is the probability the passcode has 2 each of the digits 1, 3, 5, 7, and 9? e. g. What is the probability the passcode contains 2 each of 5 different letters