1
$\begingroup$

If I go to a certain establishment 12 times in one year (let's just say once a month), and there's a 6.25% chance each time that I go in there that I would run into a person I know, what is the probability that I would run into a person I know at least one time during the course of those 12 occurrences?

Can you tell me the probability and exactly how you derived that answer?

$\endgroup$
  • $\begingroup$ If applicable, see the self-study tag wiki. (I'm guessing you're not just asking out of curiosity, but if you are, more power to you!) $\endgroup$ – Nick Stauner Jul 31 '14 at 1:25
2
$\begingroup$

P(run into the person at least once) + P(run into the person never) = 1

That is, you either run into the person at least once, or you never run into the person at all.

P(run into the person never) = $(1-.0625)^{12}$

That is, the chance that you don't run into the person during a given visit is (1-.0625). The chance that you don't run into the person in any one of those 12 visits is $(1-.0625)^{12}$.

So,

P(run into the person at least once) = 1 - P(run into the person at least once) = $1-(1-.0625)^{12}$.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.