A hacker is trying to guess someone's password. The hacker knows (somehow) that the password is 10 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.​

The probability that the hacker guesses the password on his first try is:

P = 1/(62^10) = 1.19*10^(-18)

We know that the password is 10 characters long.

In each one of these, we can put.

One lower case letter (26 of these)

One upper case letter (26 of these)

one numerical digit (10 of these)

So, for every single digit, we have a total of:

26 + 26 + 10 = 62 options

Now we can find the total number of different passwords, which will be equal to the product between the number of options for each one of the characters.

We know that for each character we have 62 different options.

And we have 10 characters.

Then the product between the numbers of options is:

C = 62^10

Then if the hacker does a random guess, the probability that the random guess is correct is one over the total number of possible combinations.

P = 1/C = 1/(62^10)

The probability that the hacker guesses the password on his first try is:

P = 1/(62^10) = 1.19*10^(-18)

If you want to read more about probability, you can read:

so, converting firstly the mixed fractions to improper fractions and then "adding".