Passwords can have 7 characters. Each character can be an uppercase or lowercase letter, a digit (there are 10 digits), or one of the special characters from the set (@, #,$,%}. a. How many passwords can be made if any character can be used in any position? b. How many passwords can be made if the first character must be a letter? c. How many passwords can be made if the first character must be a letter and the second character must be a special character? d. How many passwords can be made if you cannot repeat any character? e. How many passwords can be made if there must be at least one special character in the password? [Hint: What is the only other option to having at least one special character?]

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