Question

The number of errors on a typed page is Poisson with mean 2.5 per page. 

A. What is the probability that there are no errors on a page? 

B. What is the probability mass function for X, the number of pages out of ten with no errors on it? 

C. Find the exact and approximate probability that X=0.

D. A book of 100 pages has 95 pages with at least one error. Five pages are selected at random and without replacement. Let X denote the number of pages from the five that are selected that have no errors on it.

 i) What is the exact and approximate probability that X is at least one? 

ii) What are the mean and standard deviation of X?

Answer 1