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0580/22 Oct/Nov 2021, Question 16: Combined Events with Two-Way Tables

Cambridge IGCSE Mathematics 0580 · Paper 22 (Extended) · Calculator · 4 marks

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The question, in short

Sachin randomly selects one of the first three multiples of 3 and one of the first three primes, then adds them to get a score; complete an addition table and find a conditional probability.

Summarised in our own words. Use the official paper for the exact wording and any diagrams.

Part (a) · 2 marks

Fill in the missing entries of the addition table showing sums of the multiples of 3 and the prime numbers.

  1. 1Top row: 3, 6, 9 (first three multiples of 3); left column: 2, 3, 5 (first three primes)
  2. 2Row 2: 5, 8, 11
  3. 3Row 3: 6, 9, 12
  4. 4Row 5: 8, 11, 14

Answer| + | 3 | 6 | 9 | | 2 | 5 | 8 | 11 | | 3 | 6 | 9 | 12 | | 5 | 8 | 11 | 14 |

Part (b) · 2 marks

Knowing the total is even, work out the probability that 9 is one of the two chosen values.

  1. 1Even scores: 8, 6, 12, 8, 14, so 5 even scores
  2. 2Even scores using 9: 12 (3 + 9) and 14 (5 + 9), so 2
  3. 3P = 2/5

Answer2/5

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Also searched as: 0580/22/O/N/21 · 0580_w21_qp_22 · 0580 w21 22 · question 16.
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