Question 1

Two fair spinners, each numbered 1 to 8, are spun. The numbers they land on are added up. What is the probability the total is 16?

Accepted Answer

1. Identify the total number of outcomes for each spinner (8).
2. Determine the specific outcome needed on each spinner to achieve the target total (16). The only combination is 8 + 8.
3. Calculate the probability of this outcome for one spinner (P(8) = 1/8).
4. Since the spinners are independent, multiply the probabilities for each spinner to get the combined probability: P(8 and 8) = P(8) * P(8).
5. Calculate the final answer: 1/8 * 1/8 = 1/64.

Question 2

What mistakes do candidates make on this AQA GCSE question?

Accepted Answer

✗ Adding the probabilities (1/8 + 1/8 = 2/8 = 1/4). You must multiply probabilities for independent 'AND' events.
✗ Thinking there are two ways to get 16 (e.g., spinner 1 is 8, spinner 2 is 8 and vice versa), but this is the same single outcome.
✗ Incorrectly calculating the product, e.g., 8 * 8 = 16.

Two fair spinners, each numbered 1 to 8, are spun. The numbers they land on are added up. What is the probability the total is 16?

How to approach this question

Full Answer

Common mistakes

Practice the full AQA GCSE Statistics Higher Tier Paper 1

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