The mean number of defective products produced in a factory in one day is 21. What is the probability that in a given day there are exactly 12 defective products?
I get some big numbers when I try to answer this question and they don't make sense !
I used a Poisson Distribution calculator to get the answer
0.0116
But when I use my calculator to figure it out I get 1.0917004899798243054141947918587e-13
Where am I going wrong?
I use the basic formula for Poisson Distribution
The mean is 21
and X is 12
Poisson is used when n tends to infinite and the probability tends to zero. In my opinion you should try using Binomial Distribution.