There is an example, in short.
You have got $n$ binary values and chromosome $X$ has $k$ values of 1 and $(n-k)$ values of 0. Chromosome $Y$ is made by mutation of $x$, where the mutation is just reverse values in $x$ to $y$, so $y$ has $k$ values of 0 and $(n-k)$ values of 1. And every mutation has the probability of $p$.
Find and Expected Value of the number of values of 1 which has chromosome $Y$.
Please guys, I just need a right distribution of this value. Expected value will be easy. Thanks!