Poison distribution probability

The25thHour

Hey, would really appreciate some help with this.

Estimate the number of accidents a company can expect during mining operations. The average number of accidents on this type of mining site is .5 and follows a poisson distribution.

Calculate the probability that
(i) less than 2 accidents on site A
(ii) more than 4 accidents on site A
(iii) 3 or more accidents in total on all 3 sites

So, is it something like this?
Less than 2 accidents, P(X<2) = P(0)+P(1) because the probability of less than two is the same as zero?
I am confused

The25thHour

where, λ=2 and e=2.718
e-λ = (2.718)-2 = 0.135.

This is just from an example and while I can see the process I don't know how to go about calculating (2.718)-2,
so how do you go about it using a calculator?
Thanks

LeixlipRed

To calculate [latex]e^{-\lambda}[/latex] you use the [latex]e^x[/latex] button on your calculator where [latex]x = -\lambda[/latex].

You're right on the first question anyway. Less than two accidents is no or 1 accident. What about the others?

The25thHour

LeixlipRed wrote: »

To calculate [latex]e^{-\lambda}[/latex] you use the [latex]e^x[/latex] button on your calculator where [latex]x = -\lambda[/latex].

Sorry can you just expalin this a bit more, so what do I press first on the calculator and do I need to put it on any modes first. So say I am looking to get the above where, λ=2 and e=2.718, how do I get this?
Sorry, I'm so bad at this stuff.

LeixlipRed

Explaining how to use a calculator over the internet isn't easy. I would imagine that you'd have to press shift first and then the [latex]e^x[/latex] button would be over the ln button possibly. It might not be [latex]e^x[/latex] either it might be e with a blank box in the power.

The25thHour

LeixlipRed wrote: »

Explaining how to use a calculator over the internet isn't easy. I would imagine that you'd have to press shift first and then the [latex]e^x[/latex] button would be over the ln button possibly. It might not be [latex]e^x[/latex] either it might be e with a blank box in the power.

Thanks