# Confidence Interval for Poisson Distribution

#### Florencefrenita

##### New Member
Hi ,

I am trying to calculate a 90% Confidence Interval for a Poisson Distribution.

The Question is as below. Please let me know how is the first equation and second equation formed.

#### Dason

##### Ambassador to the humans
If you knew what lambda was would you be able to calculate probabilities for the poisson distribution?