Answer
The probability is $\frac{5}{6}$.
Work Step by Step
We know that there are six outcomes, so $\text{n}\left( \text{S} \right)=\text{ 6}$.
The event of stopping on yellow can be represented by
${{\left( \text{E} \right)}_{\text{yellow}}}\text{ }=\text{ }\left\{ 1 \right\}$
There is one outcome in this event, so $\text{n}{{\left( \text{E} \right)}_{\text{yellow}}}=\text{ 1}$.
The probability of stopping on yellow is given below, $\text{P}{{\left( \text{E} \right)}_{\text{yellow}}}\text{ = }\frac{\text{n}{{\left( \text{E} \right)}_{\text{yellow}}}}{\text{n}\left( \text{S} \right)}\text{ = }\frac{1}{6}\text{ }$
And the probability of not stopping on yellow is given below,
$\begin{align}
& {{\text{P}}_{\text{not yellow}}}\text{ = 1}-\text{ }{{\text{P}}_{\text{yellow}}} \\
& \text{= 1}-\text{ }\frac{1}{6}\text{ } \\
& \text{= }\frac{5}{6}
\end{align}$
