Question

a book has four misprints per page(on avarage ),what is the probabilitythat a page open at random will have no misprints on it?

Answer 1

Let $X=$ the number of misprints per page: $X\sim Po(\lambda).$

Given $\lambda=4.$

$$P(X=0)=\dfrac{e^{-4}(4)^0}{0!}=e^{-4}\approx0.01831564$$