Calculating Probability of 3 Pennies in 30 Boxes Using Poisson Distribution

[little neutrino]

One hundred pennies are being distributed independently and at random into 30 boxes, labeled 1, 2, ..., 30. What is the probability that there are exactly 3 pennies in box number 1?

I tried using a Poisson distribution f(x) = (e^-λ)*(λ^x)/x! , with λ = 100/30 = 10/3 and x = 3. I got 0.22021 (5 s.f.), but the answer key is 0.22345. Am I using the wrong distribution? Thanks!

 

[RUber]

For anyone penny, what is the probability that it will end up in box # 1?
Use a binomial distribution...N = number of pennies. k = 3. p = probability of landing in box #1.

 

[little neutrino]

For anyone penny, what is the probability that it will end up in box # 1?
Use a binomial distribution...N = number of pennies. k = 3. p = probability of landing in box #1.

Ok I got it! Thanks! :)