Question

Three Lights of Yellow, Green and Red color blinks after every 36,24 & 40 seconds respectively if they all started at 6:00 am then at what time they will blink together again​

Answer 1

Given: Three lights of yellow, green, and red color blink after every $36,24 and 40$second, and they all are started at $6.00am.$

We have to find the time when they all will blink together again.

=>The first light flashes at $36$s., $72$s, $108$s, … In other words, multiples of $36$seconds.

=>The second light flashes at $24$s, $48$s, $72$s, … In other words, multiples of $24$seconds.

=>The third light flashes at $40$s, $80$s, $120$s, … In other words, multiples of $40$seconds.

Hence, the times when the lights flash together are common multiples of$36$,$24$ and $40$seconds.

i.e.

=>LCM of $36,24and40=360$

That means after $6mins.$

Hence, they all will blink together again at $6.06am.$