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Here are three lamps.
lamp C
lamp B
lamp A
Lamp A flashes every 20 seconds.
Lamp B flashes every 45 seconds.
Lamp C flashes every 120 seconds.
The three lamps start flashing at the same time.
How many times in one hour will the three lamps flash at the same time?​

Respuesta :

Answer with step-by-step explanation:

First of all, we need to calculate how many times the 3 lamps flash in a minute. We can do this by finding their LCM (least common multiple), which is 360. 360 is equivalent to 6 minutes, so that is going to be our test time. Lamp a flashes every 20 seconds, so 360/20 = 18 flashes. Then, 360/45 = 8 flashes. Finally, 360/120 = 3 flashes. 18 + 8 + 3 = 29 flashes per 6 minutes. If so, we multiply 29 by 10, because 60 minutes per hour ÷ 6 minutes = 10. So 29 × 10 = 290 flashes per hour

Hope this helped! (brainliest please)

Answer:b

Step-by-step explanation:

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