P(X>=2) given X<=4 and λ = 1 :
Poisson Distribution falls under Discrete Random Variable so considering all the discrete points in the range {2,3,4}.
= P(X=2) + P(X=3) + P(X=4)
= (e^(-1) * 1^2)/2! + (e^(-1) * 1^3)/3! + (e^(-1) * 1^4)/4!
= (1/e) * (½ + 1/6 + 1/24)
= 17/24e
= 0.26058
Now we need to find out
P(X>=2 / X<=4)
= ( P(X=2) + P(X=3) + P(X=4) ) / ( P(X=0) + P(X=1) + P(X=2) + P(X=3) + P(X=4) )
= 0.26058 / 2.70834
= 0.0962