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Question
A red light flashes 3 times per minute and a green light flashes 5 times in two minutes at regular intervals. If both lights start flashing at the same time, how many times do they flash together in each hour?
A red light flashes 3 times per minute and a green light flashes 5 times in two minutes at regular intervals. If both lights start flashing at the same time, how many times do they flash together in each hour?
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Solution
The correct option is A 30
Red light flashes once in every 1/3 of a minute.
Green light flashes once in every 2/5 of a minute
Taking LCM of both the figures, we can find the time required by both to flash together = LCM of (1/3) and (2/5)=LCM of NumeratorHCF of Denominator
So, the LCM of the fractions = 2
Hence they both flash together every two minutes.
Hence in 1 hour, they will flash 60/2 = 30 times.
30
Red light flashes once in every 1/3 of a minute.
Green light flashes once in every 2/5 of a minute
Taking LCM of both the figures, we can find the time required by both to flash together = LCM of (1/3) and (2/5)=LCM of NumeratorHCF of Denominator
So, the LCM of the fractions = 2
Hence they both flash together every two minutes.
Hence in 1 hour, they will flash 60/2 = 30 times.Suggest Corrections
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