How do I evaluate this

Adairy farmer accidentally allowed some of his cows to graze in a pasture containing weeds that would contaminate the flavor of the milk from this herd. the farmer estimates that there's a a 9 9% chance of a cow grazing on some of the flavorful weeds. (a) under these conditions, what is the probability that none of the 16 16 animals in this herd ate the tasty weeds? (b) does the poisson model give a good estimate of the probability that no animal ate the weed?