A fair five-sided spinner has sides numbered 1, 1, 1, 2, 3. A fair three-sided spinner has sides numbered 1, 2, 3. Both spinners are spun once and the score is the product of the numbers on the sides the spinners land on.

Mark scheme

Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.

1. [B1] Probability distribution table with correct scores, allow extra score values if probability of zero stated
2. [B1] 2 probabilities (with correct score) correct
3. [B1] 3 or more correct probabilities with correct scores
4. [B1] FT Σp = 1, at least 4 probabilities
5. [B1] mean = (3+8+12+4+12+9)/15 = 48/15 = (3.2)
6. [M1] FT Substitute their attempts at scores in correct var formula, must have “– mean²” (condone probabilities not summing to 1)
7. [A1] 224/15 - 3.2² = 4.69 (352/75)
8. [M1] Identifying relevant scores from their mean and their table
9. [A1] Correct answer
10. [SC B1] for 4/15 with no working