The expected number of typographic errors in a page of a certain magazine is 2.What is the probability that an article of 10 pages has 2 errors?
My attempt: I thought that if $X$ is the r.v that counts the numbers of errors in this article, then it has distribution $Poisson(20)$, but the answer says it has distribution $Poisson(2)$. I don't understand why, since I thought we should consider that the errors per page are independent and then the expected number of errors in $10$ pages is $20$
Thanks!