TDSM 2.21

The probability of getting exactly $$k$$ heads on $$n$$ tosses, where the coin has a probability of $$p$$ in coming up heads on each toss follows the binomial distribution: $$P(X=k) = B(k,n,p) = C^k_n p^k(1-p)^{n-k}$$

The probability of getting $$k$$ or more heads on $$n$$ tosses: $$P(X\geq k) = \sum_{i=k}^n B(i,n,p) = \sum_{i=k}^n C^i_n p^i(1-p)^{n-i}$$