Question

The traffic lights at three different road crossing change after every 60 seconds, 90 seconds and 120 seconds respectively. If they change simultaneously at 12:40 am , at what time they will change simultaneously again?

Answer 1

Hey friends here is your answer :-

Find the Prime Factors:

60= 2*2*3*5

90= 2*3*3*5

120= 2*2*2*3*5

Find the LCM:

LCM =2*2*2*3*3*5= 360

Convert 360 seconds to mins:

360 seconds = 360 ÷ 60 mins

360 seconds  = 6 mins

Find the time it will change together again:

12:40 am + 6 mins =  12:46 am

HOPE IT HELPED YOU.......