Question: 2014 Winter Final - 14
We flip a fair coin repeatedly and independently, resulting in a sequence of heads ($H$) and tails
($T$). We stop flipping the coin as soon as this sequence contains $H$ or $TTTT$. What is the
probability that this sequence contains at most two $T$s?
(a)
6/8
(b)
4/8
(c)
5/8
(d)
7/8