If we have a number of **equally likely **and **mutually exclusive** outcomes for an experiment, then we can use the **simple probability** formula detailed below:

**Exercise**

Let’s complete exercise 3 from pages 294 to 296 of the core textbook:

The answers are below:

**Expected Frequency**

Based on this formula we have the concept of expected frequency.

If I role a dice 60 times, I would expect about 10 of the results to be “5” (though clearly I won’t always get exactly 10 “5”s. We say that the **expected frequency** of the **outcome** 5 is 10. We can calculate this as the **probability** multiplied by the **number of trials**, i.e. 1/6 x 60

**Example**

**Exercise**

Let’s complete exercise 4 from pages 296 and 297 of the core textbook:

The answers are below: