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Two light houses flash their lights every 30 seconds and 40 seconds respectively. Given that they flashed together at 10:40 a.m, what time will they next flash together

2 Answers

1 vote
They will flash at the same time every 120 minutes. 10:40+ 120 min= 12:40. They will both flash again at 12:40
User Sinkeat
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4 votes
Given that their least common multiple would be 120, they would flash together 2 minutes later, at 10:42
User Tvs
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