Athief steals an atm card and must randomly guess the correct four-digit pin code from a 9-key keypad. repetition of digits is allowed. what is the probability of a correct guess on the first try?

Step-by-step explanation:

The number of keys on the keypad = 9

The number of digits in the required pin code = 4

If repetition is allowed then , the number of possible codes will be

Then , the probability that the choosen pin code is correct is given by :-

The probability of Geometric distribution formula :

, where p is the probability of success and x is the number of attempt.

Using geometric probability , the probability of a correct guess on the first try is given by :-

combine all like terms then its just a 2 step equation