Question

At two crossroads signals, lights change after every 25 seconds and 45 second respectively. If they changed together at 9.20 am , then when will they change together next?

Answer 1

This is ur ans hope it will help you

Answer 2

The lights will change together at 9:23:45 am

1) Both the lights will change together at an common multiple.

2) So, we can find the Least Common Multiple of both the lights i.e 25 and 45

3) 25=5*5 and 45= 5*9

The LCM would be 5*5*9 = 225

4) Hence both lights will change after 225 seconds i.e 3 min 45 seconds