Question

The traffic lights at three different crossings changes after every 35 seconds ,42 seconds and 70 seconds respectively if they change simultaneously at 9 am at what time will the change simultaneously next

Answer 1

Solution :-

Given that traffic light at three different crossing change after every 35 seconds, 42 seconds and 70 seconds respectively..

Prime Factors: -

→ 35 = 5 x 7

→ 42 = 2 x 3 × 7

→ 70 = 2 x 5 × 7

→ LCM: 2 × 3 × 5 × 7 = 210 seconds.

Convert 210 seconds to mins: -

→ 210 seconds = 432 ÷ 60 mins

→ 210 seconds = 3 mins + 30 seconds.

Therefore,

→ The Time Lights will change simultaneously next = 9A.M + 3 mins 30 seconds = 9:03:30 A:M . (Ans.)

Hence, At 9:03:30 A:M The traffic lights change simultaneously next .