Describing Probabilities and Equally Likely Outcomes (5)

Recognise that probabilities range from 0 to 1 (ACMSP117)

List outcomes of chance experiments involving equally likely outcomes and represent probabilities of those outcomes using fractions (ACMSP116)

LO: To describe probabilities using fractions, decimals and percentages
Know:

  • The probability is the chance of an event occurring.
  • How to answer questions to collect data
  • The difference between categorical and numerical data

Understand:

  • That probability ranges from 0 to 1

Do:

  • I can describe probabilities between 0 and 1.

Describing Probabilities

Probabilities of events can be described in a range of 0 to 1.

The probability of an event occurring can never be less than 0.

A probability of 0 means that the event is impossible to occur.

The probability of an event occurring can never be more than 1.

A probability of 1 means that the event is certain to occur.

Probabilities can also be described with fractions.

A probability of 1/2 has an even chance of occurring.

A probability of less than < 1/2 would be unlikely of occuring.

A probability of more than > 1/2 would be likely to occur.

Equally-likely Outcomes

Equally-likely outcomes means that there is an equal chance for all events to occur.

For example, the chance of landing a heads or tails is equal when flipping a coin, so that is an equally-likely event.
The chance of picking an even number is the same as the chance of picking an odd number, so those events are also equally-likely.

This is an equally-likely event because the spinner has an equal chance of landing in the red, green, orange and blue sections.

This is not an equally-likely event because the spinner has an unequal chance of landing in the blue, red, green and pink sections because the pink and blue sections are unequal.

Teaching Ideas

Equally-likely Outcomes Videos