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Math Help - Word Problem Help Please

  1. #1
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    Word Problem Help Please

    This is my 9th grade Algebra homework word problem that I'm currently having trouble understanding exactly what to do;


    "Two trains are on the same track a distance of 100 km apart heading towards one another, each at a speed of 50 km per hour. A fly starting out at the front of one train flies towards the other at a speed of 75 km per hour. Upon reaching the other train, the fly turns around and continues toward the first train. How many kilometers does the fly travel before getting squashed in the collision of the two trains?"

    Any help would be greatly appreciated, thank you!
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  2. #2
    Super Member Matt Westwood's Avatar
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    Famous trick question. I'm ashamed your teacher asked it.

    All you need to do is ask yourself:

    1. How fast are the trains going? Therefore, how long will it be before they collide?

    2. How fast is the fly going? How long is it going to be flying before being crushed?

    3. Multiply the speed of the fly by the length of time before the trains collide.

    Notice there is no need to add up all those vanishing distances to try and find the limit of a sequence of blah, blah, yibbedy yadayada ...
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  3. #3
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    So would that be 1 hour times 75 km/h?
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  4. #4
    Super Member Matt Westwood's Avatar
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    Got it in one.

    So how far do you travel if you go at 75 km per hour for an hour? and you're done. Teech will be impressed.
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  5. #5
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    Quote Originally Posted by redx47 View Post
    So would that be 1 hour times 75 km/h?
    Yep.
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  6. #6
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    Thank you very much! That was extremely helpful! (thanks button clicked) My teacher is obsessed with word problems so I'm sure I'll be using this site a lot...
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  7. #7
    Super Member Matt Westwood's Avatar
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    You're very welcome! Word problems are a nightmare but the only way to get over the hurdle is to do lots of them. Uurgh.

    Of course, if you *like* word problems you have a career as an *applied* mathematician.
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