Question 1158785: Elroy and Herbert are product testers at a company that makes mouthwash. If Elroy can complete a gargling cycle once every 20 seconds, and Herbert can complete a gargling cycle once every 30 seconds, how many seconds will it take them together to complete a combined total of 15 gargling cycles?
Found 2 solutions by ikleyn, josgarithmetic:
Answer by ikleyn(52778)   (Show Source):
You can put this solution on YOUR website! .
Every 60 seconds, E makes 3 cycles, while H makes 2 cycles; together they make 3+2 = 5 cycles each minute.
So, they need  = 3 minutes to complete 15 cycles. ANSWER
Solved, explained and completed.
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Such problems, and this one, in particular, are intended for the 3-rd - 4-th grade young students,
who don't know equations, at all.
So, what I presented in my post, is a STANDARD method for them to solve such problems.
It is their FIRST acquaintance with the joint work problems --- therefore, the solution method should be adequate.
From this point of view, any complications in solving method (as the other tutor presents) are NOT appropriate for them.
If you want to see many other problems, solved in this way, look into the lesson
- Special joint work problems that admit and require an alternative solution method
in this site.
Answer by josgarithmetic(39617)  (Show Source):
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