Year 11
Foundation

Calculate probabilities of independent events

Year 11
Foundation

Calculate probabilities of independent events

Lesson details

Key learning points

  1. In this lesson, we will learn how to calculate probabilities of outcomes for independent events from tree diagrams

Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

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3 Questions

Q1.
Here is the first branch of a probability tree diagram.
An image in a quiz
Correct answer: A
B
C
D
Q2.
Here is the first branch of a different probability tree diagram. What should the missing probability be?
An image in a quiz
Correct answer: 0.18
0.41
0.82
18
Q3.
This tree diagram shows Amir taking red and blue counters from a jar. He replaces the counter after he has picked one up.
An image in a quiz
A
B
Correct answer: C
D

3 Questions

Q1.
For the probability tree shown, which calculation will find the probability of red followed by blue happening?
An image in a quiz
0.2 + 0.2
0.2 x 0.2
Correct answer: 0.2 x 0.8
0.8 x 0.8
Q2.
The probability that Amy and Joe win a game of chess is shown in the tree diagram. Work out the probability that over 2 games Amy wins twice.
An image in a quiz
Correct answer: 0.09
0.49
0.6
0.9
Q3.
James draws this probability tree diagram to help him calculate probabilities of taking sweets from a bag. What assumptions has James made when completing this probability tree?
An image in a quiz
All probabilities add to 1 on each branch.
Correct answer: He replaces the first sweet he takes.
It doesn’t matter if he eats the first sweet he takes.