Thus the Poisson approximation can be used to compute binomial probabilities for large n. It also makes the analysis of such probabilities easier.Typical examples are:

• number of bit errors in a received binary data file
• number of typographical errors in a printed page

Example 4 Suppose there is an error probability of 0.01 per word in typing. What is the probability that there will be more than 1 error in a page of 120 words?

Solution:  Suppose X is the RV representing the number of errors per page of 120 words.

                  where Therefore,