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Hong Kong
Stage 1 - Stage 3

Traffic Light Problems

Interactive practice questions

Traffic lights showing green, red and yellow lights are set up on a race track. A race car approaching the lights is equally likely to see a green, red or yellow light.

This is because:

the three lights stay on for the same amount of time.


the race car driver is driving at a constant speed.


the lights are the same size.

Less than a minute

A traffic light is green for $35$35 seconds, amber for $5$5 seconds and then red for $50$50 seconds. What is the probability that the next person at the traffic lights gets a:

On the island of Timbuktoo the probability that a set of traffic lights shows red, yellow or green is equally likely. Christa is travelling down a road where there are two sets of traffic lights.

A traffic light at a railway crossing has a chance of $0.3$0.3 of being yellow.

Three cars approach the light separately at different times throughout the day. What is the probability that each of the cars approaches a yellow light?

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