GCSE Secondary Maths Age 13-17 - Probability & Statistics: Probability - Explained

The video tutorial explains the probability of a car being stopped by two sets of traffic lights, A and B, using a tree diagram. It details the steps to complete the diagram, ensuring all branches add up to one. The tutorial then calculates the probability of Mark being stopped by only one set of lights, concluding that it is more likely he was stopped by lights B. The video also discusses the allocation of marks for solving the problem, emphasizing the importance of understanding tree diagrams and probability calculations.

What is the probability that a car is stopped by lights A?

• 0.3

• 0.6

• 0.4

• 0.5

If a car is stopped by lights A, what is the probability that it is not stopped by lights B?

• 0.7

• 0.8

• 0.3

• 0.2

What should the sum of probabilities on each branch of a tree diagram equal?

• 2

• 1.5

• 1

• 0.5

What is the probability that Mark is stopped only by lights A?

• 0.48

• 0.58

• 0.38

• 0.28

What is the probability that Mark is stopped only by lights B?

• 0.58

• 0.48

• 0.38

• 0.28

Which set of lights is Mark more likely to be stopped by?

• Neither

• Both equally

• Lights B

• Lights A

How many marks are allocated for correctly completing the tree diagram?

• 1

• 2

• 4

• 3