Acomputer system allows each user to choose a password using any combination of uppercase letters (a- z), lowercase letters (a-z), digits (0-9) and special characters f@$%& ! ? g. how many di erent passwords are possible: 1. if any combination is possible and passwords are of length 8 exactly? 2. if passwords can't start with a special character and passwords are of length 8 exactly? 3. if any combination is possible and passwords can be any length between 8 and 10 characters? 4. if any combination is possible and passwords are of length 8 exactly but there must be at least one special character or one digit?