Sir i am suck for this question

5. On average a secretary makes 3 typo errors per page of her typing. If the Poisson distribution is assumed to hold, what are the probabilities that in her next 2 pages of the typing she [a] makes less than 3 typo errors? (3 marks) [b] makes more than 5 typo errors? (4 marks) [Hint: Sum of 2 independent Poisson random variables is again Poisson distribution with parameter being the sum of the parameters.]