AMC8 2027 - Self-practice Set 7 Question 2

Question 2

A 60-second traffic-light cycle has 25 seconds green, 5 yellow, and 30 red. At a uniformly random arrival time, what is the probability of having to stop at yellow or red?

$\frac{1}{4}$
$\frac{1}{3}$
$\frac{5}{12}$
$\frac{1}{2}$
$\frac{7}{12}$