SOLUTION: A certain machine is composed of three led light blink in varied materials . the red light blink every 8 second the blue light blink every 12 second and the yellow light blink eve

Question 1119481: A certain machine is composed of three led light blink in varied materials . the red light blink every 8 second the blue light blink every 12 second and the yellow light blink every 18 second. If all light blinke together at exactly 3pm how mqny times theyvwill blink again altogether until 3:30pm?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A certain machine is composed of three led light blink in varied materials . The red light blinks every 8 seconds; the blue light blinks every 12 seconds; and the yellow light blinks every 18 seconds. If all lights blink together at exactly 3pm how many times will they blink again altogether until 3:30pm?
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Find the least common multiple of 8,12, and 18.
8 = 2^3
12 = 2^2*3
18 = 2*3^2
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The lcm has each prime factor in its highdest power
lcm = 2^3*3^2 = 8*9 = 72
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All lights will blink at 3pm, 3pm+72sec, 3pm+2*72sec, etc
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# of seconds in 30 min = 30*60 = 1800
1800/72 = 25
Ans:: 25 times
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Cheers,
Stan H.
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