Answer:
1.83%
Step-by-step explanation:
For the expected value of 4 cases per 1000 children. We can use a formula for Poisson distribution to calculate the probability that none of the 1000 students would contract the flu:
[tex]P(X = 0) = \frac{\lambda^ke^{-\lambda}}{k!}[/tex]
[tex]P(X = 0) = \frac{4^0 e^{-4}}{0!}[/tex]
[tex]P(X = 0) = \frac{1}{e^4} = 0.0183 [/tex]
So the probability of this to happens is 1.83%