When we talk about a theoretical probability that a coin will land on tails of 1/2, what we really mean is that if we tossed the coin many many times, over time the proportion of times it would land on tails would be about 1/2 of the total number of times we tossed it. This is the idea of relative frequency, defined as:

In general, relative frequency serves as a good estimate of the (theoretical) probability of an event

Example

Exercise

Let’s complete exercise 18B on pages 297 and 298 of the textbook:

The answers are below: