Question 981948
 
Given:
A newspaper find the mean number of typos per page is 3.
Find probability that
(A) exactly 4 typos are found on a page
(B) at most 4 typos are found on a page
(C) more than 4 typos are found on a page.
 
Solution:
This is a Poisson distribution with {{{lambda=3}}}.
The Poisson distriibution is
P(n)={{{lambda^n*e^(-lambda)/n!}}}
 
(A) n=4
P(4)={{{lambda^4*e^(-lambda)/4!=0.16803}}}
(B) n<=4
P(n<=4)=P(0)+P(1)+P(2)+P(3)+P(4)
=0.04979+0.14936+0.22404+0.22404+0.16803
=0.81526
(C) n>4
P(n>4)=1-P(n<=4)=1-0.81526
=0.18474