0580/31 Oct/Nov 2025, Question 22: HCF and LCM
Cambridge IGCSE Mathematics 0580 · Paper 31 (Core) · Calculator · 5 marks
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The question, in short
Find when trains leaving every 20 and 35 minutes from 09 30 next depart together, and give the range of a 97 km distance rounded to the nearest km.
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Part (a) · 3 marks
Find the next time after 09 30 when both trains, departing every 20 and 35 minutes, leave together.
- 120 = 2 × 2 × 5, 35 = 5 × 7
- 2LCM = 2 × 2 × 5 × 7 = 140 minutes = 2 h 20 min
- 309 30 + 2 h 20 min = 11 50
Answer11 50
Part (b) · 2 marks
Complete the inequality giving the lower and upper bounds for d, 97 km to the nearest kilometre.
- 1Nearest km: half a km either side of 97
- 296.5 ≤ d < 97.5
Answer96.5 ≤ d < 97.5
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Also searched as: 0580/31/O/N/25 · 0580_w25_qp_31 · 0580 w25 31 · question 22.
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