MHB Guessing a three digit pin code from an 8 key keypad

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The discussion centers on calculating the probability of correctly guessing a three-digit PIN code from an 8-key keypad, allowing for repetition of digits. Participants clarify that this scenario involves permutations since the order of digits matters, making 123 different from 321. The fundamental counting principle is applied to determine the total number of possible PIN combinations. Given the parameters, there are 512 possible PIN codes (8^3). The probability of a correct guess on the first try is therefore 1 in 512.
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Hello, the problem is as follows. I'm not sure if it is a permutation or combination problem. It says if a thief steals and ATM card and must randomly guess the correct three digit pin code from an 8 key keypad. Repetition of digits is allowed. What is the probability of a correct guess on the first try?
 
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jridgeman99 said:
Hello, the problem is as follows. I'm not sure if it is a permutation or combination problem. It says if a thief steals and ATM card and must randomly guess the correct three digit pin code from an 8 key keypad. Repetition of digits is allowed. What is the probability of a correct guess on the first try?

How many PIN codes are possible...can you apply the fundamental counting principle to answer this question?
 
I'll just add on to Mark's comment that PINs are order-sensitive. 123 is not the same as 321.
 

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