Question

Kiara sets up a passcode on her tablet, which allows only four digit codes. She has heard that it’s more secure if a digit is repeated in the passcode. A spy sneaks at Kiara’s tablet and sees her fingerprints on the screen over three 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

Let:

A = Unlock the table on the first try

a = Number of Possible right digits

N = Total number of possible digits

the probability the spy is able to unlock the tablet on his first try is:

$\begin{gathered} P(A)=\frac{a}{N} \\ P(A)=\frac{1}{10} \end{gathered}$