Question

the traffic lights at 3 different road crossings change after 40 seconds, 30 seconds and 90 seconds respectively if they change simultaneously at 9:am after what time will they change again simultaneously ? answer with steps

Answer 1

Answer:

9:00:10 am

Step-by-step explanation:

first we will find out h c f of 40 sec , 30 sec , 90 sec

40 = 2 ×2×2×5      30 = 2× 3 ×5           90 = 2×3×3×5

h c f = 10

now we will add  10 sec in 9:am

and that would be the next time of changing

which is 9:00:10 am

hope helpful