1.) A hacker is trying to guess someone's password. The hacker knows (somehow) that the password is 15 characters long,

[answerhappygod]

1.) A hacker is trying to guess someone's password. The
hacker knows (somehow) that the password is 15 characters long, and
that each character is either a lowercase letter, (a, b, c, etc),
an uppercase letter (A, B, C, etc) or a numerical digit (0, 1, 2,
3, 4, 5, 6, 7, 8, or 9). Assume that the hacker makes random
guesses.
What is the probability that the hacker guesses the
password on his first try? Enter your answer as a decimal or a
fraction, not a percentage.