Suppose that, on average, in every two pages of a book there is one typographical error, and

Question:

Suppose that, on average, in every two pages of a book there is one typographical error, and that the number of typographical errors on a single page of the book is a Poisson r.v. with λ = 1 / 2. What is the probability of at least one error on a certain page of the book? Interpret your result.