Y is a Poisson distributed random variable with mean λ = 7.2. Determine P(3 ≤ Y ≤ 4 ).
a) 0.0658
b) 0.2450
c) 0.5618
d) 0.0945
e) 0.1300

Question

Y is a Poisson distributed random variable with mean λ = 7.2. Determine P(3 ≤ Y ≤ 4 ).
a) 0.0658
b) 0.2450
c) 0.5618
d) 0.0945
e) 0.1300

anonymous · Answer

I think its A correct me if i am wrong

kirbykirby · Answer

Hmm I don't get that result. 
Remember the probability mass function for the Poisson is:
$$ P(X=k)=\frac{e^{-\lambda}\lambda^k}{k!}, \text{for }k=0,1,2,\ldots$$
So, $$ P(3\le X\le4)=P(X=3)+P(X=4)$$.. make you you include both x=3 and x=4 since they are both included in the inequality.

anonymous · Answer

Oh I did not realize there was formula, i was going off a graph