A keypad at the entrance of a building has 10 buttons labeled 0 through 9. What is the probability of a person correctly guessing a 9-digit entry code if they know that no digits repeat?
Answer:
the probability of a person correctly guessing a 9-digit entry code if they know that no digits repeat is 0.1
Step-by-step explanation:
We know that probability= number of required outcomes /number of all possible outcome.
From the given information;
the number of required outcome is guessing a 9-digit = 1 outcome
the number of all possible outcome = ¹⁰C₉ since there are 10 numbers and 9 number are to be selected.
Since there are only 9-digit that opens the lock;
the probability of a person correctly guessing a 9-digit entry code is
[tex]P =\dfrac{1}{^{10}C_9}[/tex]
[tex]P =\dfrac{1}{\dfrac{10!}{9!1!}}[/tex]
[tex]P =\dfrac{1}{10}[/tex]
P = 0.1
