Question

What is the probability of flipping a coin 7 times and getting heads 5 times? Round your answer to the nearest tenth of a percent.

Answer 1

For a fair coin,
Probability of a head, P(H) = 1/2 = 0.5
Probability of a tail , P(T) = 1/2 = 0.5
The number of possible outcomes is small enough to simply list the outcome:
The possible outcomes of flipping a coin 7 times and getting heads 6 times are these 7 possibilities:
THHHHHH
HTHHHHH
HHTHHHH
HHHTHHH
HHHHTHH
HHHHHTH
HHHHHHT
The probability of EACH of the above outcomes is
= (0.5)(0.5)(0.5)(0.5)(0.5)(0.5)(0.5)
= (0.5)⁷
Since there are 7 possibilities and since the probabilities of every outcome is identical, the probability of rolling the 7 outcomes is,
= 7 x probability of each outcome
= 7 x (0.5)⁷
= 0.5468
= 5.468%
= 5.5% (nearest tenth)