Question

The traffic light at three different signal points change after every 15 seconds,30 seconds and 45 seconds respectively. If all change simultaneously at 8:15:20 hours,then when will they change again simultaneously?

Answer 1

              Here  Is Your Answer !!                

Step-by-step explanation:

We have to find LCM of the time

it'll be.....

15= 3x5

30= 3x5x2

45= 3x5x3

:.Common factors = 5x3

:.Noncommon factors = 2x3

:.LCM = Common factors x Noncommon factors

         = 2x3x5x3

          =90

It means both 3 signal lights will change simultaneously after 90 seconds. Then next changing time will be 90 seconds past 8:15:20

=> 90seconds+8hours 15minutes 20seconds

=>8hours 16minutes 50seconds

=>8:16:50

:.All signals will change again simultaneously at 8:16:50.