Since you're needing to find the probability of something

**not** happening (four times in a row), I'm not sure how you'd go about answering that question without taking that into account.

What other method or formula did they give you to use? Thanks!

They've defined "Theoretical Probability" as the ratio of the number of elements in an event to the number of equally likely elements in a sample space.

From the text:

"For example, the sample space for tossing two coins, {(H, H), (H, T), (T, H), (T, T)}, has four equally likely elements and the event of landing two heads, {(H, H)}, has one element. The theoretical probability that two heads will show when two coins are tossed is 1/4."

So...

The event of "0 heads" equals the event of "three tails". There's only one element in that event so the ratio is 1/8.

For the event of "1 head", I count three different elements:

I'm struggling to determine how you'd calculate that same number of elements in that event using combinations or permutations.