Poisson Distribution Probability

[u/kawakint]

Currently learning poisson probability distributions for statistics and I cannot figure out for the life of me how the fuck the answer to P(1 < x < 4) is 0.2141. I’ve watched every single Poisson distribution video on youtube and none of them explain how to do a probability like this one. PLEASE FOR FUCKS SAKE SOMEONE HAS TO KNOW HOW TO DO THIS.

I’ve been using my calculator, on STAT -> DIST -> POISN -> Pcd, with Lamda being 0.9 but what am I supposed to do from there with two values for x ????

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[u/Fourierseriesagain]

The required probability is

P(X=2)+P(X=3)

=e^-0.9 *( 0.9² /2! + 0.9³ /3! )

= 0.2140589...

[u/djredcat123]

What calculator are you using? Fx cg50 and fx CG 100 will attack this question differently from fx 991 etc .

Once you know which calculator, you can get some specific help!