A theoretical probability is a probability based on counting the number of desired outcomes from a sample space where all individual outcomes are equally likely.

Calculating theoretical probabilities from lists (one event)

Maths

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. 

Probability: theoretical probabilities

__________ probability is a probability based on counting the number of desired outcomes from a sample space where all individual outcomes are equally likely.

What is the probability that this spinner lands on 'A'?

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

A counter is picked at random from the bag. What is the probability that it contains the letter B?

A regular six-sided dice is rolled. What is the probability of rolling a 4?

A regular six-sided dice is rolled. Which event has a probability of $${4}\over{6}$$?

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

Which letter on the probability scale represents a probability of 0.5?

The spinner is divided into equal-sized sectors. What fraction of the spinner is labelled 'win'?

The spinner is divided into equal-sized sectors. {{}}% of the spinner is labelled 'lose'.

A trial has three possible outcomes: {A, B, C}. P(A) = $${2}\over{7}$$. P(B) = $${1}\over{7}$$. P(C) = $${4}\over{7}$$. Which outcome is most likely to happen?

The probability on an outcome is 25%. Approximately how many times could you expect the outcome to occur in 500 trials?

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