Question

the traffic light at three different signal change after 48 sec ,72 sec,and 108 sec.if they change at 7 am simultaneously how many times they will change between 7am to 7.30 am simultaneously​

Answer 1

Step-by-step explanation:

48+72+108=928sec

1min=60Sec

15.46 min= 928 sec

1min=60.02

1hr= 60min

half n hr= 30 min

30min=15.46+14.54

928+14.54×60.02

928+872.77

1800.77

convert to min 1800÷60=30

Answer 2

Answer:

4 times

Step-by-step explanation:

48 = 2×2×2×2×3 = $2^{4}$ × 3

72 = 2×2×2×3×3 = 2³ × 3²

108 = 2×2×3×3×3 = 2² × 3³

LCM(48, 72, 108) = $2^{4}$ × 3³ = 432 seconds ⇒ Every 432 sec. the traffic lights will be changed simultaneously

432 ÷ 60 = 7.2 minutes = 7 minutes and 12 seconds

30 minutes ÷ 7.2 = 4 times