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Equally Likely Outcomes

Understand that 'equally likely' means every outcome has exactly the same chance of occurring; identify whether a given situation has equally likely outcomes (a fair coin, a fair die, a spinner with equal sections) or unequally likely outcomes (a bag with more of one colour, a spinner with unequal sections)

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What a learner can do afterwards

  • Explain that a fair coin has equally likely outcomes because heads and tails each have the same chance
  • Identify whether a spinner with unequal sections has equally likely outcomes or not, and explain why
  • Give an example of a situation with equally likely outcomes and one without, explaining the difference

The lesson

Flip a coin. It can land on heads or tails. Each one has exactly the same chance of happening. When every outcome has exactly the same chance, we call them equally likely outcomes.

Red1Blue1Green1
All three parts are the same size, so red, blue, and green are equally likely.
Try it together

Mia has a bag with 4 red counters and 1 yellow counter. She pulls one out without looking. Red is more likely than yellow, because there are more red counters. This bag does not have equally likely outcomes.

Red4Yellow1
Good to know

To check if outcomes are equally likely, compare the amounts. The same amount for each outcome means equally likely. More of one than another means not equally likely.

Equally likely means every outcome has the exact same chance, so compare the amounts to check.

Watch it

Where it sits

Where this leads

Jobs that lean on this skill. Follow one to see everything it is built on.

Then practise

8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.

Equally Likely Outcomes · Mathematics, ages 9 to 10 · LightMySky