- Exacly 1 head
- At least 1 head
The figure below has n as the x axis and the two different probabilites as y axis. As you can see, the "exactly 1 head" probability decreases with n while the "at least 1 head" probability increases with n.
n = 1:16; pExactly1 = n./2.^n; plot(n, pExactly1); grid on hold on pAtLeast1 = 1-(1-0.5).^n; plot(n, pAtLeast1) legend('exactly 1 heads', 'at least 1 heads') xlabel('n'); ylabel('p')Note that you can also get probability of at least 1 heads with this sum: pExactly1Head + pExactly2Heads + ... + pExactlyNHeads, where
pExactlyKHeads = nchoosek(n,k) * ph^k * (1-ph)^(n-k)Even simpler: 1 - pExactly0Heads = 1 - nchoosek(n,0) * ph^0 * (1-ph)^(n-0).
For more information, visit Khan Academy.