Question 181315This question is from textbook Teaching Textbooks
: Edwin can drop a piece of luggage off the top of headquarters and then record the results once every 4 minutes. Hewitt can do the same every 5 minutes. How many minutes will it take them together to drop their luggage and record the results a (combined) total of 18 times?
I tried this equation where x= minutes
5x + 4x = 18x
My problem is that the x's don't seem to have the same value. I think I need to find out how many tries they each need and multiply that by the minutes, but I don't see how I can tell how many tries they each need!
Thanks for helping!
This question is from textbook Teaching Textbooks
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! Edwin can drop a piece of luggage off the top of headquarters and then record the results once every 4 minutes. Hewitt can do the same every 5 minutes. How many minutes will it take them together to drop their luggage and record the results a (combined) total of 18 times?
I tried this equation where x= minutes
5x + 4x = 18x
My problem is that the x's don't seem to have the same value. I think I need to find out how many tries they each need and multiply that by the minutes, but I don't see how I can tell how many tries they each need!
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To do 18 drop tests, it would take Edwin 72 minutes, and Hewitt 90 minutes.
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Then look at what part of the total test (18 drops) they do per minute.
For Edwin, it's 1/72 (overall job per minute)
For Hewitt, it's 1/90
Now it's the same units, so you can add them.
Together they do 1/72 + 1/90 = 5/360 + 4/360 = 9/360.
That's the job/time, so invert that.
360/9 = 40 minutes.
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It's a tricky thing to visualize.
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