Poisson distribution question why my formula is off and I have to multiply by 100,000?

35 Views Asked by At

Observations at a certain large company that on average, there is a server outage every 6 months. What is the probability of getting through a year without any server outage at all?

I solved this question as so.

There are 12 months in a year

We are looking for the probability of no outages in a year which is P(0 outages).

Poisson Formula

$12^0$*$e^{-12}$/0!

This is where I get a very small result which I multiply by 100,000 = 6.144... * $10^{-6}$

final result = 0.6144

I am not sure why I am multiplying by 100,000 Its just what makes seance to me which gives a result that could make seance.

Terrible way to go about it but I am struggling to understand how to approach this question?