Along a highway there are two sections of road works under construction. These two sections are controlled by red and green traffic lights. Anne has calculated that there is a 90% chance that the first set of lights are green and that is a 70% chance that the second set of lights are green. Calculate the probability that Anne will have to stop at least once.
1st light: P(green light) = 0.9
2nd light: P(green light) = 0.7

not stop at all means both lights are green

P(stop at least once) = 1 – P(not stop at all)
= 1 – P(Green, Green)
= 1 – 0.9 × 0.7
= 0.37 to