Question

There are two sets of traffic lights outside Eric's house. One day, he times how often they change. Set A turns green every 60 seconds. Set B turns green every 70 seconds. At midday precisely they both turn green together.

At what time will they both turn green together again?


Pls I need help, I'm stuck​

Answer 1

12:07 or 7 minutes into midday

Explanation:

You have to find the Least/lowest common multiple (LCM) of 60 and 70 which is 420.

So you divide 420 by 60 (60 second in a minute) which gives you the answer

7. So if you add 7 minutes into midday/add 7 minutes into 12:00,

it gives you the answer

12:07 or 7 minutes into midday

Answer 2

12:07pm

Explanation:

first common multiple of 60 and 70 is 420

420 s = 7 mins