Question

Avery sets up a passcode on her tablet, which allows only 9 digit codes. A spy sneaks a look at Avery’s tablet and sees her fingerprints on the screen over nine numbers. What is the probability the spy is able to unlock the tablet on his first try? Express your answer as a fraction.

Answer 1

We will have the following:

Since the spy sees fingerprints in 9 digits, then she used 9 different numbers for the password, so the posibility will be the following:

$P=\frac{1}{10}\cdot\frac{1}{9}\cdot\frac{1}{8}\cdot\frac{1}{7}\cdot\frac{1}{6}\cdot\frac{1}{5}\cdot\frac{1}{4}\cdot\frac{1}{3}\cdot\frac{1}{2}\Rightarrow P=\frac{1}{5443200}$