Skip to main content
OlympiadHQ

Browse · MATH

Print

jmc

counting and probability intermediate

Problem

If you flip a fair coin four times, what is the probability of flipping at least three heads in a row? Express your answer as a common fraction.
Solution
The quickest way to solve this problem is to count the number of outomes that have three heads in a row, as we already know very clearly that there are outcomes total. So, HHHH, HHHT, THHH are the only 3 outcomes that have three consecutive heads. So, our answer is .
Final answer
\frac{3}{16}