Good Afternoon Mohamed Karam,

The answer you provided was very good of:

=.10*20=2

P(x=k)=e^- *^k / k!

p(x=0)=e-2 * 2^0 /0!=.1353

p(x=1)=e-2 * 2^1 /1!=.2706

p(x=2)=e-2 * 2^2 /2!=.1353

p(x=3)=e-2 * 2^3 /3!=.1804

p(x=4)=e-2 * 2^4 /4!=.0902

I will pay you much more if you can answer a little bit more to that question. Using that example, find the probability of having exactly 5 vehicles arrive in 20 seconds.