Question

The traffic light at three different road crosses change after every 48 seconds. 72
seconds and 108 seconds. If they start changing simultaneously at 8 am, after how much​

Answer 1

Step-by-step explanation:

LCM of 48,72,108 is 432

divide 432 by 60 since there are sixty seconds for a minute

then,we obtain 7.2 minutes

add 7.2 to 8 AM then,next bell ring at 8:07 am 29 seconds

please mark my answer as brainiest answer

Answer 2

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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