Asked by Matt
                I am very confused on how to figure out the below math problem: 
A traffic light changes every 30 seconds. Another traffic light changes every 40 seconds. Both lights just changed. After how many minutes will both lights change at the same time again?
Please help me.
            
        A traffic light changes every 30 seconds. Another traffic light changes every 40 seconds. Both lights just changed. After how many minutes will both lights change at the same time again?
Please help me.
Answers
                    Answered by
            Ms. Sue
            
    Find the least common multiple of 30 and 40.
30, 60, 90, 120, 150
40, 80, 120, 160
 
    
30, 60, 90, 120, 150
40, 80, 120, 160
                    Answered by
            Matt
            
    The least common multiple of 30 and 40 is 120. 
How did you know that I need to find the least common multiple of 30 and 40.
Would 120 be the answer? So both lights would change at the same time again after 120 minutes.
    
How did you know that I need to find the least common multiple of 30 and 40.
Would 120 be the answer? So both lights would change at the same time again after 120 minutes.
                    Answered by
            Ms. Sue
            
    You need to know what time they'd change at the same time.
Yes, 120 is correct.
    
Yes, 120 is correct.
                    Answered by
            Matt
            
    What was the indicator in the word problem is what I am trying to figure out that told you multiple? 
    
                    Answered by
            Ms. Sue
            
    I just thought about it.  No magic tricks.
    
                    Answered by
            Matt
            
    The reason why I was asking is I printed out a paper to look out for key words in math word problems. 
Thank you for helping me solve the problem.
    
Thank you for helping me solve the problem.
                                                    There are no AI answers yet. The ability to request AI answers is coming soon!
                                            
                Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.