0580/23 Oct/Nov 2025, Question 25: Conditional Probability
Cambridge IGCSE Mathematics 0580 · Paper 23 (Extended) · Non-calculator · 3 marks
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The question, in short
Mahir randomly selects one value from 5, 10, 15 and one from 4, 5, 6, then sums them; a partly filled addition grid is shown. Complete the grid and find a conditional probability.
Summarised in our own words. Use the official paper for the exact wording and the diagram.
Part (a) · 1 mark
Fill in the missing totals in the addition table for each pair of chosen numbers.
- 15 + 4 = 9, 5 + 5 = 10, 5 + 6 = 11
Answer| + | 5 | | 4 | 9 | | 5 | 10 | | 6 | 11 |
Part (b) · 2 marks
Knowing the sum is odd, work out the probability that 15 is one of the two values added.
- 1Odd totals: 9, 11, 15, 19, 21 (5 outcomes)
- 2Of these, 15 is added in 15 + 4 = 19 and 15 + 6 = 21 (2 outcomes)
- 3P = 2/5
Answer2/5
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Also searched as: 0580/23/O/N/25 · 0580_w25_qp_23 · 0580 w25 23 · question 25.
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