Light A flashes every 5 seconds.
Light B flashes every 6 seconds.
Light C flashes every 7 seconds.
All three lights flash at the same time.
Work out how long it will take for all three lights to flash at the same time again.
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Markscheme
Prime Factors, HCF and LCM Questions
16 exam-style questions on Oxford AQA IGCSE Maths Prime Factors, HCF and LCM. Each one has a worked solution and a mark scheme showing where the marks go.