Solution
= Solution
The number of heads has the <binomial distribution>. Choosing the $k$ head positions gives
$$
\boxed{\mathbb P(\text{exactly }k\text{ heads})
=\binom nk p^k(1-p)^{n-k}}.
$$
= Solution
The number of heads has the <binomial distribution>. Choosing the $k$ head positions gives
$$
\boxed{\mathbb P(\text{exactly }k\text{ heads})
=\binom nk p^k(1-p)^{n-k}}.
$$