O-LevelMathematicsNumber4024/13 · May/June 2025 · Q113 Marks
A green light flashes every 12 minutes. A red light flashes every 45 minutes. The two lights flash together at 9 am. Find the next time when the two lights will flash together.
- A green light flashes every 12 minutes. A red light flashes every 45 minutes. The two lights flash together at 9 am. Find the next time when the two lights will flash together.[3]
Mark scheme
Marking points from the official mark scheme (May/June 2025). The mark or mark type is shown in brackets.
- [3] 12:00 or 12 pm
- B2 for 180 identified as LCM soi
- or M1 for 2² × 3 or 3² × 5 seen
- or list of at least three times 12, 24,36... etc and 45, 90, 135... etc soi
- or list of at least three times eg 9.12, 9.24, 9.36 etc and 9.45, 10.30, 11.15 soi
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