Question

A fair coin is tossed 8 times. What is the probability of getting at least 6 heads

Answer 1

This is solved by using the binomial distribution:
\[P(6\ heads)=\left(\begin{matrix}8 \\ 6\end{matrix}\right)0.5^{6}0.5^{2}\]
\[P(7\ heads)=\left(\begin{matrix}8 \\ 7\end{matrix}\right)0.5^{7}0.5^{1}\]
\[P(8\ heads)=\left(\begin{matrix}8 \\ 8\end{matrix}\right)0.5^{8}0.5^{0}\]
The required probability is found by adding the above three values of probability.