Question

The traffic lights at there different roads crossing change after every 48 second, 72 second and 108 second respectively. If they change simultaneously at 7 am, at what time will they change simultaneously again? ​

Answer 1

Answer:

Step-by-step explanation:

LCM of 48 72 and 108=432

the will change after 432 seconds=432/60 mins=7 mins 12 seconds.

or at 7:07 approximately.

this is the least time .

if you want only in minutes then it will be 36 mins or 7:36 can also be a time

pls mark as brainliest

hope it helps...

Answer 2

$\large \green{ \fcolorbox{gray}{black}{ ☑ \: \textbf{Verified \: answer}}}$

If the traffic lights change simultaneously at 8 a.m, then they will change simultaneously again after the LCM of the duration i.e. 48 s, 72 s and 108 s.

LCM of these durations by prime factorisation

48 = 2 × 2 × 2 × 2 × 3 = 2⁴ × 3

72 = 2 × 2 × 2 × 3 × 3 = 2³ × 3²

108 = 2 × 2 × 3 × 3 × 3 = 2² × 3³

LCM of 48, 72 and 108 is 2⁴ × 3³ = 432 seconds.

Hence, They will change after 432 seconds i.e. 7 minutes 12 seconds.

The traffic lights will change after:

8 am + 7 minutes 12 seconds

08 : 07 : 12 am