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.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
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.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
\frac{3}{16}
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.
train