# Question #ba1dc

Jun 5, 2015

There are four possible sequences of flips. Each is equally likely.

Since since the combination of tails twice in a row is one of four, you can calculate the probability as $\frac{1}{4}$.
This can also be done by multiplying the probability of a particular outcome by the probability for each trial. You know that the probability of tails for each trial is $\frac{1}{2}$. You can calculate the probability for two tails in a row as:
$\frac{1}{2} \cdot \frac{1}{2} = \frac{1}{4}$