MYP · Mathematics MYP Year 2
Probability and Outcomes
22 min readStandardRecurring content across unit tests and end-of-year exams; assessed mainly through MYP Criterion A (Knowing & Understanding) and Criterion D (Applying in real-life contexts)
Probability in MYP2 is really one idea wearing six different costumes: dice, coins, spinners, marbles, trees, Venn diagrams. Every question reduces to counting — how many outcomes are possible, and how many count as a 'win'. Get the total number of outcomes wrong (writing 6 instead of 36 for two dice, or adding instead of multiplying for combined events) and the rest of the answer collapses even with perfect method afterwards.
Overview — The Shape of This Topic
What this chapter is really testing
- Probability questions always come back to counting: how many total outcomes are there, and how many of them count as favourable.
- You'll meet in six costumes — dice, coins, spinners, marbles — but the structure never changes.
- The jump from Year 1 is combining events: a die AND a coin, two dice together, a spinner AND a marble draw. Combined totals multiply, they never add.
Examiners like writing a wrong student claim straight into the question (see the sum-of-7 dice problem) and asking you to judge it. That means you need to defend your counting in words, not just produce a fraction.
The shape of the chapter
Command terms this topic uses constantly
| Command term | What it demands | AO | Mark-earning move |
|---|---|---|---|
| State | Give a short answer with no working required. | AO1 | 1 mark for the correct value/fraction alone — justification not needed, but the value must be correctly written (e.g. as a fraction, not left as a raw ratio like 1:6). |
| Identify | Pick out or name a specific feature from given information. | AO1 | 1 mark per correct item named — for combined events this usually means naming both individual sample spaces before anything is calculated. |
| Calculate | Show the method and reach a numerical answer. | AO2 | Marks for correct substitution into AND the final simplified value — an unsimplified fraction can lose the last mark. |
| Explain | Give reasons connected to the maths, not a restated observation. | AO3 | No credit for 'because it's random' alone — must reference sample size, independence, or the specific rule being tested. |
| Compare | State similarities/differences between two given quantities, with values. | AO3 | Needs BOTH a numerical statement (which is bigger/smaller) and a reason — one without the other usually caps the mark. |
Key point
Every mark in this topic depends on correctly counting the TOTAL number of equally likely outcomes first. Get that denominator wrong (36 vs 6 for two dice) and every probability calculated afterwards is automatically wrong, even with perfect method.
Overview