A vessel contains `N` molecules of an ideal gas. Dividing mentally the vessel into two halves `A` and `B`, find the probability that the half `A` contains `n` molecules. Consider the cases when `N = 5` and `n = 0,1,2,3,4,5`.

Explanation

The probabilities that the half `A` contains `n` molecule is
`N_(C_n) xx 2^-N = (N!)/(n!(N - n)!) 2^-N`.