Imagine that a school recently issued requests that all students change their login passwords to improve security and prevent unauthorized access to student accounts.

One of your friends claims that the best password (from a purely probabilistic perspective) is one that is short but highly complex. They decide to create a randomly generated 7-character password that contains both upper- and lower-case letters (A – Z and a – z) and numbers (0 to 9). What is the probability of guessing their password based on these conditions?