# How do you calculate theoretical probability?

##### 1 Answer

Nov 6, 2014

**Theoretical Probability**

Assume that each outcome is equally likely to occur.

Let

The probability of the event

where

**Example**

What is the probability of rolling a multiple of 3 when you roll a standard die once?

Since all outcomes are 1 through 6, we have the sample space

Since all multiple of 3 are 3 and 6, we have the event

Hence, the probability of rolling a multiple of 3 is

I hope that this was helpful.