Two fire sirens give alarms at intervals of 5/7, 7/8 hours. Since these two fire sirens sounded an alarm at 04:00 on Friday at the same time, on which day and at what time do they alarm together again?
The Answer to the Question
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Here's the Solution to this Question
To determine when the two alarms will sound together again, we need to find the lest common multiple between the two intervals.
LCM(5,7) is given by
HCF(7,8) = 1
Therefore, LCM = 35
This means that the two sirens will alarm together again after 35 hours. Since they both sounded at 04:00 of Friday, we add 35 hours to this time and get, 15:00 on Saturday.