Answer:
N= 3
Step-by-step explanation:
given data
mean [tex]\lambda[/tex] = 3
provide repairs at least = 25%
solution
as here for poisson distribution
P(X=k) = [tex]\frac{(\lambda )^ke^{-\lambda }}{k!}[/tex] ......................1
so here
P(X>n) = 0.25
and
P(X>n) = [tex]e^{-3 } \sum_{X=n}^{\infty } \frac{(3 )^k}{k!}\geq 0.25[/tex] ..............2
so
P(X>3) = 0.3528
and
P(X>4) = 0.1847
so here
N= 3