I'm stuck solving a Poisson distribution question, not entirely sure how I go about actually calculating the answer
So a call centre receives telephone calls at a rate of 12 per hour, the clerk working at the centre wants to go for a break. How long must her coffee break be if she is to have a 50/50 chance of not missing a call?
So I'm pretty confident about my reasoning for this;
$$P(N(t) = 0) = e^{-12t} \frac{(12t)^0}{0!} \leq 0.5$$
However i'm clueless how to actually solve this? Do I have to rearrange for $t$? and how do I use the 0.5 probability in this question?