poisson distribition question

[Jellekool]

Hello everyone,

I don't really understand the answer of question a. The question was: Find the probability that on any given day there will be fewer than two breakdowns on this highwayduring the morning rush hour. Additional information: on average: 3,2 breakdowns per day occur. isn't it 0,1712 + 0,0408, because there can also be 0 breakdowns?

Thanks in advance!

 

[GretaGarbo]

You are correct that "there can also be 0 breakdowns". But please not that the table give the cumulative distribution function.

Here are both of them:

            p       cdf
1  0.04076220 0.0407622
2  0.13043905 0.1712013
3  0.20870248 0.3799037
4  0.22261598 0.6025197
5  0.17809279 0.7806125
6  0.11397938 0.8945919
7  0.06078900 0.9553809
8  0.02778926 0.9831702
9  0.01111570 0.9942859
10 0.00395225 0.9982381
11 0.00126472 0.9995028