Question

the green light of a crossing goes of amd off. every 15 sec and that of the next crossing goes and off every 20sec .if they are lighted together at 4 am. when will the again go on together.​

Answer 1

Answer:

8.07.12 am

Step-by-step explanation:

Find the Prime Factors:

48 = 2⁴ x 3

72 = 2³ x 3²

108 = 2² x 3³

Find the LCM:

LCM = 2⁴ x 3³

LCM = 16 x 27 = 432

Convert 432 seconds to mins:

432 seconds = 432 ÷ 60 mins

432 seconds  = 7.2 mins

7.2 mins = 7 mins 12 seconds

Find the time it will change together again:

8 am + 7 mins 12 seconds = 8.07.12 am

I hope it will help you❤️❤️