The quantity of lost books in a library can be distributed with a Poisson distribution with parameter $\lambda$. The propability that one book is missing at the end of a year is $p$. After the first year $n$ books are missing. Find a cumulative distribution function!
So I only new, that $\lambda=n\cdot p$ and $F_X(x)=\mathrm{e}^{-\lambda}\frac{\lambda^{x}}{x!}$. How I can compute the right distribution function for this case? Maybe with an approximation of an binomial-distribution?
Have you any hints for me? Thank you!