Vocabulary

Uniform probability model – each outcome has an equal probability of happening.

Theoretical probability – what should happen in a probability experiment based on the uniform probability model.

Experimental probability – what actually happens in a probability experiment based on outcomes in trials during the experiment.

Concepts

Writing the theoretical probability of an outcome.

Rules

1. Find the total number of outcomes that can happen, for example, the number of cards or the sections of the spinner.
2. Determine the number of times the desired outcome in the question can happen.
3. Divide the desired outcomes by the total possible outcomes. 
4. Simplify the fraction.

Example

If you drew a card at random from those pictured below, what is the theoretical probability of choosing a yellow card?

Select the correct answer choice.

$\frac{3}{4}$

$\frac{1}{2}$

$\frac{3}{8}$

$\frac{5}{8}$

Solution

5 of the 8 cards are yellow. Therefore, the theoretical probability is $\frac{5}{8}$.

Pre-requisite Skills

Write Probability as Percentage, Fraction and Decimals (6.9.1)

Probability of Simple Events (7.10.1)