In this activity, we will look at a mix of probability questions.
Here is a recap of what we've learned on probability.
A probability is given as a decimal, fraction or a percentage e.g 0.5, ½ or 50%
Remember that lists of possible outcomes, tables and tree diagrams are all useful ways to help you work out probabilities.
1) Probability of an event happening = Number of ways the event can happen ÷ Total number of possible outcomes
2) The probability of something not happening = 1 minus the probability of it happening.
3) You should also know when to add probabilities (or) and when to multiply them (and).
Example 1: Calculate the probability of throwing a 2 or a 5 on a six-sided die.
1/6 + 1/6 = 2/6 (OR rule, so we add)
Example 2: Calculate the probability of getting a heads on a coin and a 4 on a six-sided die.
1/2 × 1/6 = 1/12 (AND rule, so we multiply)
4) Relative frequency can be used to estimate an experimental probability.
For example, if a coin is flipped 200 times, how many times can we expect it to land on tails?
The formula we use is : the probability x the number of times it was flipped
½ × 200 = 100
So, 100 is the number of times we might expect to throw tails.
Let's have a go at the questions now.
Remember that you can look back to this introduction at any time by clicking on the pink help button