**Probability** is a measure of the likelihood of an event occurring.

$\text{Probability of event occurring}=\genfrac{}{}{0.07ex}{}{\text{number of ways event can occur}}{\text{total number of possible outcomes}}$

The **sample space** of an event occurring is the set of possible outcomes.

The **complement** of an event occurring is the event not occurring.

If the probability of an event occurring is P(A), then the complement is 1 − P(A), often denoted as P(A').

**What is the sample space of the event?**

The set of possible outcomes is {red, blue, yellow}.

**What is the probability Haley selects a blue token?**

$\begin{array}{rcl}\text{Probability of event occurring}& =& \genfrac{}{}{0.07ex}{}{\text{number of ways event can occur}}{\text{total number of possible outcomes}}\\ & =& \genfrac{}{}{0.07ex}{}{\text{7}}{\text{2 + 7 + 3}}\\ & =& \genfrac{}{}{0.07ex}{}{\text{7}}{\text{12}}\end{array}$

**What is the probability Haley does not select a blue token?**The probability of an event not occurring is 1 minus the probability of the event occurring.

$1-\genfrac{}{}{0.07ex}{}{\text{7}}{\text{12}}=\genfrac{}{}{0.07ex}{}{\text{5}}{\text{12}}$