Cambridge questions are written in precise mathematical English. If you know exactly what product, difference, justify and estimate ask you to do, you will not lose marks answering the wrong question.
| Term | What it means | Example |
|---|---|---|
| probability | How likely something is, from 0 to 1. | P(head) = 1/2. |
| outcome | One possible result. | Rolling a 4. |
| event | The outcome or outcomes you are interested in. | Rolling an even number. |
| impossible | It can never happen; probability 0. | Rolling a 7 on a dice. |
| certain | It must happen; probability 1. | Rolling less than 7. |
| even chance | Just as likely as not; probability 1/2. | A fair coin landing heads. |
| equally likely | Every outcome has the same chance. | The six faces of a fair dice. |
| favourable outcome | An outcome that counts as the event happening. | 2, 4 and 6 for “even”. |
| complement | The event not happening. | P(not A) = 1 − P(A). |
| mutually exclusive | Two events that cannot both happen. | Rolling a 2 and a 5. |
| trial | One go of an experiment. | One roll of the dice. |
| experimental probability | Successes divided by trials. | 8 sixes in 60 rolls. |
| theoretical probability | What should happen, from the outcomes. | 1/6 for a six. |
| expected number | Probability × number of trials. | 1/6 × 60 = 10. |
| bias | When outcomes are not equally likely. | A weighted spinner. |
| random | Chosen so every outcome has an equal chance. | Drawing without looking. |