Question

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 lowercase, an uppercase letter or a numerical digit. Assume that the hacker makes a random guess.

What is the probability that the hacker guesses the password on his first try? Enter your answer as a decimal or a fraction.

Answer 1

There are 26 possible lowercase letters, 26 possible uppercase letters, and 10 possible numbers (0-9). 26+26+10=62 That means there's a 1/62 chance that they get one letter right. But there's 15 letters. They're chance would decrease each time to get it exact. 1/62 divided by 15/1 = 1/832 So there is a 1 in 832 chance that the hacker guesses it correct first try with that information.