An LED signboard flashes orange light every 15 seconds and green light every 25 seconds. After what minimum interval of time will they flash together?

75 seconds

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70 seconds

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50 seconds

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30 seconds

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Solution

The correct option is A 75 seconds
From the ladder method, the LCM of 15 and 25 is:
LCM (15, 25): 3 × 5 × 5 = 75

Thus, the signboard would flash both orange and green lights after 75 seconds.

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An LED signboard flashes orange light every 15 seconds and green light every 25 seconds. After what minimum interval of time will they flash together?

The correct option is A 75 secondsFrom the ladder method, the LCM of 15 and 25 is: LCM (15, 25): 3 × 5 × 5 = 75 Thus, the signboard would flash both orange and green lights after 75 seconds.

The correct option is A 75 seconds
From the ladder method, the LCM of 15 and 25 is:
LCM (15, 25): 3 × 5 × 5 = 75

Thus, the signboard would flash both orange and green lights after 75 seconds.