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Math Help - The bathtup-Problem

  1. #1
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    The bathtub-Problem

    Hello!

    I've encountered a difficult problem here and would like some help.
    It would be great for my understanding If you could help me solve it with fractions.



    A bathtub is filled in 5 minutes and emptied in 10 minutes when the plug is pulled out. How much time will it take to fill the bathtub if you forget to insert the plug?
    Last edited by Benjy; September 8th 2011 at 03:05 PM.
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  2. #2
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    Re: The bathtup-Problem

    Quote Originally Posted by Benjy View Post
    Hello!

    I've encountered a difficult problem here and would like some help.
    It would be great for my understanding If you could help me solve it with fractions.



    A bathtub is filled in 5 minutes and emptied in 10 minutes when the plug is pulled out. How much time will it take to fill the bathtub if you forget to insert the plug?
    rate tub is filled ... \frac{1 \, tub}{5 \, min}

    rate tub is emptied ... \frac{1 \, tub}{10 \, min}

    combined rate ... \frac{1 \, tub}{5 \, min} - \frac{1 \, tub}{10 \, min} = ?
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  3. #3
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    Re: The bathtup-Problem

    Quote Originally Posted by Benjy View Post
    Hello!

    I've encountered a difficult problem here and would like some help.
    It would be great for my understanding If you could help me solve it with fractions.



    A bathtub is filled in 5 minutes and emptied in 10 minutes when the plug is pulled out. How much time will it take to fill the bathtub if you forget to insert the plug?
    I'm not sure whether there is a specific answer for this question, here is a try:

    If x is defined as the volume of the bathtub, then x/5 is the speed of water inflow per minute and x/10 is the speed of water outflow per minute. Then you have a net inflow rate of y=(x/5-x/10).

    Hope this helps
    Last edited by Vingar; September 8th 2011 at 02:35 PM.
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  4. #4
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    Re: The bathtup-Problem

    Quote Originally Posted by Vingar View Post
    I'm not sure whether there is a specific answer for this question ...
    then you better have another look at post #2
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  5. #5
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    Re: The bathtup-Problem

    Quote Originally Posted by Benjy View Post
    Hello!

    I've encountered a difficult problem here and would like some help.
    It would be great for my understanding If you could help me solve it with fractions.



    A bathtub is filled in 5 minutes and emptied in 10 minutes when the plug is pulled out. How much time will it take to fill the bathtub if you forget to insert the plug?
    This question is very simple. If the time it takes to empty is double the time it takes to fill, it should fill in 10 minutes, since its rate of fill was cut in half. Correct?
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  6. #6
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    Re: The bathtup-Problem

    Quote Originally Posted by TheBoss View Post
    This question is very simple. If the time it takes to empty is double the time it takes to fill, it should fill in 10 minutes, since its rate of fill was cut in half. Correct?
    yes It's correct

    Thanks
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  7. #7
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    Re: The bathtup-Problem

    Quote Originally Posted by skeeter View Post
    rate tub is filled ... \frac{1 \, tub}{5 \, min}

    rate tub is emptied ... \frac{1 \, tub}{10 \, min}

    combined rate ... \frac{1 \, tub}{5 \, min} - \frac{1 \, tub}{10 \, min} = ?
    Thank you

    I understand you

    I first tried to fit it into the "distance=speed*time"-Formula but it didn't work for me
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  8. #8
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    Re: The bathtup-Problem

    Quote Originally Posted by Vingar View Post
    I'm not sure whether there is a specific answer for this question, here is a try:

    If x is defined as the volume of the bathtub, then x/5 is the speed of water inflow per minute and x/10 is the speed of water outflow per minute. Then you have a net inflow rate of y=(x/5-x/10).

    Hope this helps

    Thank you
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