Question

Three traffic lights at three different crossings change after 48
seconds , 72 seconds and 100 seconds respectively. If they all change
simultaneously at 8 am, at What time will they again change
simultaneously?
10 am
9 am
9pm
11 am​

Answer 1

Answer:

Step-by-step explanation:

The time after which they will change simultaneously = LCM(48,72,100)

48 = 2×2×2×2×3 = 2⁴×3

72 = 2×2×2×3×3 = 2³×3²

100 = 2×2×5×5 = 2²×5²

LCM = highest power of factors = 2⁴×3²×5² = 3600

So, they will change simultaneously after 3600s,i.e., after 1 hr. Therefore, they will change at 9a.m.