Question 1047843: In a light house, three light flash every 120 sec ,72sec, 135 sec simultaneously at 8:00:00 according to the watch which loses 2sec every minute.When will they flash again according to this watch?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! In a light house, three light flash every 120 sec ,72sec, 135 sec simultaneously at 8:00:00 according to the watch which loses 2sec every minute.When will they flash again according to this watch?
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Find the least common multiple or 120, 72, and 135
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120 = 10*12 = 2*5*2^2*3 = 2^3*3*5
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72 = 8*9 = 2^3*3^2
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135 = 27*5 = 3^3*5
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lcm = 2^3*3^3*5 = 72*5 = 360 seconds = 6 minutes
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Note:: 360/60 = 6 (# of times it loses 2 sec in 360 seconds)
Ans: 8:00 + 6 min - 12 sec = 8:05 + 48 sec
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Cheers,
Stan H.
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