Asked by help pls

Your home security system is disarmed when 3 different number buttons are pushed in a certain order. No button can be pushed twice! A robber attempts to break into your house.
What is the probability that he can disarm the device by randomly guessing 3 of the 10 buttons?

(buttons from 0-9)

Answers

Answered by oobleck
there are 10P3 valid ways to pick the 3 buttons
only 1 will work, so
P(works) = 1 / 10P3

actually, if the robber does not know that a digit cannot be repeated, then
P(works) = 1/10^3
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