Question
A light flashes every 15 minutes. a second light flashes every 18 minutes. both lights flash together are 2 a.m. What will the time be when they net flash together?
Answers
Reiny
1st light:
15 30 45 90 ...
2nd light:
18 36 54 72 90....
ahhh!!
So what is 90 minutes from 2:00 am ?
another way to look at it ...
What is the LCM for 15 and 18 ?
15 30 45 90 ...
2nd light:
18 36 54 72 90....
ahhh!!
So what is 90 minutes from 2:00 am ?
another way to look at it ...
What is the LCM for 15 and 18 ?
lerato
90
Mulhim
It's 3:30 am