Question

The traffic lights at three different road crossings change after every
28 seconds, 48 seconds, 64 seconds respectively. If they change
simultaneously at 7 a.m, at what time will they change simultaneously
again?​

Answer 1

Step-by-step explanation:

Consider the problem

The traffic light at three different road crossing change after every 48seconds,72seconds and 108seconds respectively

So,

48=2×2×2×2×3

72=2×2×2×3×3

108=2×2×3×3×3

Therefore, L.CM of 48,72,108 is

(2×2×2×2×3×3×3)

=432

So, time when they change again =432seconds

But we need to find time after 7am So, first we convert 432seconds into minutes.

Time=432second

=

60

432

minutes

∴Time=7 minutes12 seconds

Thus,

Required time =7am+7minutes 12seconds

=7:07:12am

Answer 2

Answer:

they will change after 7:02:20