Volume of a rectangular prism after t days












-1












$begingroup$


I'm really stuck on this question and would like some direction.



An iceberg approximates the shape of a rectangular prism and is about 800 m long, 400 m wide and 120 m thick. As it moves into warmer water it melts evenly by 1 m per day along each measurement.



Find the volume of the iceberg after 't' days



The answer in the textbook states:



$$V(t) = 38 400 000 − 464 000t + 1320t^2 − t^3$$



Any suggestion would be great










share|cite|improve this question









$endgroup$








  • 2




    $begingroup$
    I’m sure that you’ll be able to tell us your thoughts about the question.
    $endgroup$
    – mathcounterexamples.net
    Dec 31 '18 at 9:23






  • 3




    $begingroup$
    $V=(800-t)(400-t)(120-t)$
    $endgroup$
    – Mohammad Zuhair Khan
    Dec 31 '18 at 9:25










  • $begingroup$
    @mathcounterexamples.net I was initally thinking could this be a related rates question, but it doesn't seem to work out. I then tried using simultaneous equations using volume and the surface area formula but then again I don't think that is the right direction
    $endgroup$
    – user415903
    Dec 31 '18 at 9:28










  • $begingroup$
    @MohammadZuhairKhan wow I do not understand how I did not think like that, thank you so much!
    $endgroup$
    – user415903
    Dec 31 '18 at 9:32










  • $begingroup$
    @user415903 At least tell us what is the volume of a rectangular prism knowing its dimensions.
    $endgroup$
    – mathcounterexamples.net
    Dec 31 '18 at 9:32
















-1












$begingroup$


I'm really stuck on this question and would like some direction.



An iceberg approximates the shape of a rectangular prism and is about 800 m long, 400 m wide and 120 m thick. As it moves into warmer water it melts evenly by 1 m per day along each measurement.



Find the volume of the iceberg after 't' days



The answer in the textbook states:



$$V(t) = 38 400 000 − 464 000t + 1320t^2 − t^3$$



Any suggestion would be great










share|cite|improve this question









$endgroup$








  • 2




    $begingroup$
    I’m sure that you’ll be able to tell us your thoughts about the question.
    $endgroup$
    – mathcounterexamples.net
    Dec 31 '18 at 9:23






  • 3




    $begingroup$
    $V=(800-t)(400-t)(120-t)$
    $endgroup$
    – Mohammad Zuhair Khan
    Dec 31 '18 at 9:25










  • $begingroup$
    @mathcounterexamples.net I was initally thinking could this be a related rates question, but it doesn't seem to work out. I then tried using simultaneous equations using volume and the surface area formula but then again I don't think that is the right direction
    $endgroup$
    – user415903
    Dec 31 '18 at 9:28










  • $begingroup$
    @MohammadZuhairKhan wow I do not understand how I did not think like that, thank you so much!
    $endgroup$
    – user415903
    Dec 31 '18 at 9:32










  • $begingroup$
    @user415903 At least tell us what is the volume of a rectangular prism knowing its dimensions.
    $endgroup$
    – mathcounterexamples.net
    Dec 31 '18 at 9:32














-1












-1








-1





$begingroup$


I'm really stuck on this question and would like some direction.



An iceberg approximates the shape of a rectangular prism and is about 800 m long, 400 m wide and 120 m thick. As it moves into warmer water it melts evenly by 1 m per day along each measurement.



Find the volume of the iceberg after 't' days



The answer in the textbook states:



$$V(t) = 38 400 000 − 464 000t + 1320t^2 − t^3$$



Any suggestion would be great










share|cite|improve this question









$endgroup$




I'm really stuck on this question and would like some direction.



An iceberg approximates the shape of a rectangular prism and is about 800 m long, 400 m wide and 120 m thick. As it moves into warmer water it melts evenly by 1 m per day along each measurement.



Find the volume of the iceberg after 't' days



The answer in the textbook states:



$$V(t) = 38 400 000 − 464 000t + 1320t^2 − t^3$$



Any suggestion would be great







derivatives volume






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Dec 31 '18 at 9:20









user415903user415903

295




295








  • 2




    $begingroup$
    I’m sure that you’ll be able to tell us your thoughts about the question.
    $endgroup$
    – mathcounterexamples.net
    Dec 31 '18 at 9:23






  • 3




    $begingroup$
    $V=(800-t)(400-t)(120-t)$
    $endgroup$
    – Mohammad Zuhair Khan
    Dec 31 '18 at 9:25










  • $begingroup$
    @mathcounterexamples.net I was initally thinking could this be a related rates question, but it doesn't seem to work out. I then tried using simultaneous equations using volume and the surface area formula but then again I don't think that is the right direction
    $endgroup$
    – user415903
    Dec 31 '18 at 9:28










  • $begingroup$
    @MohammadZuhairKhan wow I do not understand how I did not think like that, thank you so much!
    $endgroup$
    – user415903
    Dec 31 '18 at 9:32










  • $begingroup$
    @user415903 At least tell us what is the volume of a rectangular prism knowing its dimensions.
    $endgroup$
    – mathcounterexamples.net
    Dec 31 '18 at 9:32














  • 2




    $begingroup$
    I’m sure that you’ll be able to tell us your thoughts about the question.
    $endgroup$
    – mathcounterexamples.net
    Dec 31 '18 at 9:23






  • 3




    $begingroup$
    $V=(800-t)(400-t)(120-t)$
    $endgroup$
    – Mohammad Zuhair Khan
    Dec 31 '18 at 9:25










  • $begingroup$
    @mathcounterexamples.net I was initally thinking could this be a related rates question, but it doesn't seem to work out. I then tried using simultaneous equations using volume and the surface area formula but then again I don't think that is the right direction
    $endgroup$
    – user415903
    Dec 31 '18 at 9:28










  • $begingroup$
    @MohammadZuhairKhan wow I do not understand how I did not think like that, thank you so much!
    $endgroup$
    – user415903
    Dec 31 '18 at 9:32










  • $begingroup$
    @user415903 At least tell us what is the volume of a rectangular prism knowing its dimensions.
    $endgroup$
    – mathcounterexamples.net
    Dec 31 '18 at 9:32








2




2




$begingroup$
I’m sure that you’ll be able to tell us your thoughts about the question.
$endgroup$
– mathcounterexamples.net
Dec 31 '18 at 9:23




$begingroup$
I’m sure that you’ll be able to tell us your thoughts about the question.
$endgroup$
– mathcounterexamples.net
Dec 31 '18 at 9:23




3




3




$begingroup$
$V=(800-t)(400-t)(120-t)$
$endgroup$
– Mohammad Zuhair Khan
Dec 31 '18 at 9:25




$begingroup$
$V=(800-t)(400-t)(120-t)$
$endgroup$
– Mohammad Zuhair Khan
Dec 31 '18 at 9:25












$begingroup$
@mathcounterexamples.net I was initally thinking could this be a related rates question, but it doesn't seem to work out. I then tried using simultaneous equations using volume and the surface area formula but then again I don't think that is the right direction
$endgroup$
– user415903
Dec 31 '18 at 9:28




$begingroup$
@mathcounterexamples.net I was initally thinking could this be a related rates question, but it doesn't seem to work out. I then tried using simultaneous equations using volume and the surface area formula but then again I don't think that is the right direction
$endgroup$
– user415903
Dec 31 '18 at 9:28












$begingroup$
@MohammadZuhairKhan wow I do not understand how I did not think like that, thank you so much!
$endgroup$
– user415903
Dec 31 '18 at 9:32




$begingroup$
@MohammadZuhairKhan wow I do not understand how I did not think like that, thank you so much!
$endgroup$
– user415903
Dec 31 '18 at 9:32












$begingroup$
@user415903 At least tell us what is the volume of a rectangular prism knowing its dimensions.
$endgroup$
– mathcounterexamples.net
Dec 31 '18 at 9:32




$begingroup$
@user415903 At least tell us what is the volume of a rectangular prism knowing its dimensions.
$endgroup$
– mathcounterexamples.net
Dec 31 '18 at 9:32










1 Answer
1






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oldest

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1












$begingroup$

Trying this question from the basics would be helpful.



The volume of a rectangular prism is the product of the three sides.



The initial sides are $800,400,120$ respectively.



Since each sides reduces by $1$m in one day, after $t$ days there will be a reduction of $t$ meters in each side.



Therefore, the sides of the prism, at the end of $t$ days, will be $800-t,400-t,120-t$. Therefore the volume will be the product of these three i.e. $(800-t)(400-t)(120-t)$. Expanding the products leads to the given answer.






share|cite|improve this answer









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    1 Answer
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    1 Answer
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    $begingroup$

    Trying this question from the basics would be helpful.



    The volume of a rectangular prism is the product of the three sides.



    The initial sides are $800,400,120$ respectively.



    Since each sides reduces by $1$m in one day, after $t$ days there will be a reduction of $t$ meters in each side.



    Therefore, the sides of the prism, at the end of $t$ days, will be $800-t,400-t,120-t$. Therefore the volume will be the product of these three i.e. $(800-t)(400-t)(120-t)$. Expanding the products leads to the given answer.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      Trying this question from the basics would be helpful.



      The volume of a rectangular prism is the product of the three sides.



      The initial sides are $800,400,120$ respectively.



      Since each sides reduces by $1$m in one day, after $t$ days there will be a reduction of $t$ meters in each side.



      Therefore, the sides of the prism, at the end of $t$ days, will be $800-t,400-t,120-t$. Therefore the volume will be the product of these three i.e. $(800-t)(400-t)(120-t)$. Expanding the products leads to the given answer.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        Trying this question from the basics would be helpful.



        The volume of a rectangular prism is the product of the three sides.



        The initial sides are $800,400,120$ respectively.



        Since each sides reduces by $1$m in one day, after $t$ days there will be a reduction of $t$ meters in each side.



        Therefore, the sides of the prism, at the end of $t$ days, will be $800-t,400-t,120-t$. Therefore the volume will be the product of these three i.e. $(800-t)(400-t)(120-t)$. Expanding the products leads to the given answer.






        share|cite|improve this answer









        $endgroup$



        Trying this question from the basics would be helpful.



        The volume of a rectangular prism is the product of the three sides.



        The initial sides are $800,400,120$ respectively.



        Since each sides reduces by $1$m in one day, after $t$ days there will be a reduction of $t$ meters in each side.



        Therefore, the sides of the prism, at the end of $t$ days, will be $800-t,400-t,120-t$. Therefore the volume will be the product of these three i.e. $(800-t)(400-t)(120-t)$. Expanding the products leads to the given answer.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 31 '18 at 9:34









        астон вілла олоф мэллбэргастон вілла олоф мэллбэрг

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        38.9k33477






























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