Hi everyone, as you can see this is my first post. I should start by saying that my stats is so rusty that I'm not even sure if this is a basic or advanced problem! Anyway, here goes:
I have a very large sample (~30,000,000) of particles of a known size distribution (split into 5 fractions) from which I want to pick a smaller sample (~30,000), and determine the probability of getting various different size distributions. If the original sample of M particles consists of A, B, C, D and E particles in each size fraction, and I am picking m particles, the probability of picking a, b, c, d and e particles is:
First of all, I hope that this is correct! As I said, my stats is very rusty. The problem with this is that, for example, B is 850,000 and b is 850, which is beyond the realms of Excel's calculations. Even worse, B<C<D<E!
So, my question is: is there an approximate method I could use in this case that would avoid these enormous numbers?
I hope I have explained my problem properly! Thank you in advance for any help you can give.