The probability that an event will occur is the proportion of times the event is expected to happen in a suitably large experiment.

The probability scale

Maths

Checking listing possible outcomes

Calculating theoretical probabilities from lists (one event)

Calculating theoretical probabilities from a table (one event)

Calculating theoretical probabilities from probability tree diagrams (one event)

Calculating theoretical probabilities from Venn diagrams (one event)

Comparing multiple representations to calculate theoretical probabilities

Summing probabilities

Calculating theoretical probabilities from two-way tables (two events)

Calculating theoretical probabilities from Venn diagrams (two events)

Calculating theoretical probabilities from probability trees (two events)

Comparing multiple representations to calculate theoretical probabilities for combined events

Problem solving with theoretical probability

In the future unit, pupils use their knowledge of calculating theoretical probabilities and extend this understanding to calculating conditional probabilities using all of the representations encountered in this unit.

In the prior unit, pupils learnt techniques for systematically listing all of the possible outcomes for both one event and two events. In this unit, pupils use lists of outcomes to find theoretical probabilities. 

In this unit we build upon the concept of likelihood to work more mathematically with more measurable probability using fraction and decimal representations to both interpret and calculate. We revisit and develop ways to represent and compare probabilities.

Probability: theoretical probabilities

The letter E on the scale represents a probability of {{}}%.

Which probabilities are equivalent to an 'even chance'?

What is the probability of an event that is impossible?

Which is the probability that this spinner lands on 'win'?

A trial has three possible outcomes: {A, B, C}. P(A) = $${1}\over{2}$$. P(B) = $${1}\over{3}$$. P(C) = $${1}\over{6}$$. Which outcome is most likely to happen?

The probability on an outcome is 20%. Approximately how many times could you expect the outcome to occur in 500 trials?

Which letter on the scale of likelihoods represents 'even chance'?

What does the letter A represent on the scale of likelihoods?

Which word describes the likelihood of an outcome that is guaranteed to happen?

Starter Quiz

Which letter on the scale of likelihoods represents 'even chance'?