Question

HELP ASAP

A fair coin is flipped 7 times. What is the probability that at least 5 of the flips come up heads?

Answer 1

This can be solved using the binomial distribution. Find the probabilities of exactly 5 heads, 6 heads and 7 heads and then add the three values of probability.
\[\large P(5\ heads)=7C5\times0.5^{5} \times0.5^{2}\]
\[\large P(6\ heads)=7C6\times0.5^{6}\times0.5^{1}\]
\[\large P(7\ heads)=0.5^{7}\]