please help!!!!

[kim270]

suppose that the number of accidents occuring on a highway each day is a poisson random variable with parameter\(\displaystyle x=3\)

a. find the probabilty the 3 or more accidents occur today

i have no idea where to begin with question any help would be apperiacted

 

[tkhunny]

Yikes! You REALLY have "no idea"? How can anyone possibly help you?

Pr(3 or more) = 1 - Pr(2) - Pr(1) - Pr(0)

 

[kim270]

when i tried this is what i did:
X= number acidents a day

P(X>3)= 1-P(0)-P(1)-P(2)
P(X>3)= (e^-3)3!-(e^-3)3!-(e^-3)(3!/2!)
P(X>3)= 1-O.29872-O.29872-0.149361
P(X>3)= 0.253199

But the actual answer is 0.5768

can anyone see what im doing wrong here

 

[tkhunny]

Better check that formula.

Pr(0) = e^-3*3⁰/0!
Pr(1) = e^-3*3¹/1!
Pr(2) = e^-3*3²/2!

I get 0.57681