PROBABILITY Lesson 1

Probability Is a number that shows how likely it is that an event will happen You might also hear it called chance. Can be expressed as fractions, decimals or percentages, or on a probability scale.

Probability We can look at a scale of chance to see how likely it is that something will happen

If something has a low probability, it is unlikely to happen. If something has a high probability, it is likely to happen.

Chance ½ 1 impossible Certainty Even Chance

The Language of Probability

Any number less than 1 or greater than 6. White, because there are more white marbles than any other colour.

Outcomes and Tree Diagrams Lesson 2

How to Record Probability Probability is recorded as a fraction, decimal or percent To record it as a fraction: P(event) = Number of favourable outcomes Total number of possible outcomes

An outcome is the possible result of an event or an experiment When a coin is tossed, the possible outcomes are heads or tails

HOW to Calculate Probability Figure out the denominator first (total number of outcomes) Figure out the numerator (the favourable outcome, which is what you want) Example. If I have a die, what is the probability I get an odd number?

Sometimes, it is not so easy to figure out the total number of outcomes. In that case, we need a strategy...

Sometimes, it is not so easy to figure out the total number of outcomes. In that case, we need a strategy... Lists or Tree diagrams

Tree Diagrams Line everything up into columns 1 column for each event, with columns branching off the ones before them End with an outcomes column (made by reading across tree branches)

Example: Eli spins the pointer on this spinner and rolls a number cube labelled 1 to 6 You must draw the tree diagram to represent the situation How many outcomes include rolling an odd number and spinning red?

Theoretical Probability Theoretical probability is the likelihood of an event happening based on all the possible outcomes (calculated)

Task 1 The Scenic Railroad sells tickets for trips on Saturdays and Sundays. All-day and half-day trips are available. There are adult, child, and senior fares. Draw a tree diagram to show the possible ticket types.

Task 2 Complete Investigating Probability 6.2.2

Experimental Probability Experimental Probability is a measure of likelihood of an event based on data from an experiment and is written in the form When conducting a probability experiment, create a table so that you can tally your results. P(event) = Number of times desired outcome occurs Total number of trials in the experiment