Hello everyone. I have a couple questions this time, but I think if I understand how to do this one, I'll understand the others.
A particular online banking system uses the following rules for its passwords:
a. Passwords must be 6-8 characters in length
b. Passwords must use only alphabetical and numeric characters, and must have at least one alpha and one numeric character.
c. Letters are case sensitive.
Under these rules, how many different passwords are possible?