SOLUTION: Quincy is opening a bank account. He needs to create a personal identification number (PIN) for the automated teller machine and a password for online access to his account.
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-> SOLUTION: Quincy is opening a bank account. He needs to create a personal identification number (PIN) for the automated teller machine and a password for online access to his account.
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Question 1184029: Quincy is opening a bank account. He needs to create a personal identification number (PIN) for the automated teller machine and a password for online access to his account.
1. Quincy’s PIN must be a 4-digit number.
(a) Quincy asks the bank representative if digits can be used more than once. The representative says, “Yes, allowing for repetition reduces the likelihood of someone guessing your password.” Explain why this is true and calculate the probability of someone guessing a PIN in one try under each scenario.
Allowing for repetition, there are possible PINs, and therefore the probability of guessing in one try is . If repetition is not allowed, then there are possible PINs, and the probability of guessing on one try is , slightly less than twice as likely as guessing if repetition is allowed.
John
My calculator said it, I believe it, that settles it
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