Question

Question #ba1dc

Answer 1

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

• Heads, Heads
• Heads, Tails
• Tails, Heads
• Tails, Tails

Since since the combination of tails twice in a row is one of four, you can calculate the probability as `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 `1/2`. You can calculate the probability for two tails in a row as:
`1/2 * 1/2 = 1/4`