Results 1 to 11 of 11

Math Help - HELP: Population

  1. #1
    Junior Member
    Joined
    Oct 2008
    Posts
    68

    HELP: Population

    If the world population is now 6.2 billion people and if it continues to grow at an annual rate of 1.25% compounded continuously, how long (to the nearest year) will it take before there is only 1 square yard of land per person? (The Earth contains approximately 1.68 x 10^14 square yards of land)
    Follow Math Help Forum on Facebook and Google+

  2. #2
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by dc52789 View Post
    If the world population is now 6.2 billion people and if it continues to grow at an annual rate of 1.25% compounded continuously, how long (to the nearest year) will it take before there is only 1 square yard of land per person? (The Earth contains approximately 1.68 x 10^14 square yards of land)
    you must use the same formula for exponential growth that i gave you last time.

    P(t) = P_0 e^{rt}

    you want the time when P(t) = 1.68 \times 10^{14}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Oct 2008
    Posts
    68
    Quote Originally Posted by Jhevon View Post
    you must use the same formula for exponential growth that i gave you last time.

    P(t) = P_0 e^{rt}

    you want the time when P(t) = 1.68 \times 10^{14}
    How about the 1.25% and the 6.2 billion people? Are they part of the formula?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by dc52789 View Post
    How about the 1.25% and the 6.2 billion people? Are they part of the formula?
    1.25% means the rate of growth is 0.0125, the 6.2 billion is the P_0
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Oct 2008
    Posts
    68
    Quote Originally Posted by Jhevon View Post
    1.25% means the rate of growth is 0.0125, the 6.2 billion is the P_0
    So...how do we write that up in exponential growth formula?
    P(t) = 6.2 e^0.0125t?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by dc52789 View Post
    So...how do we write that up in exponential growth formula?
    P(t) = 6.2 e^0.0125t?
    yes, if you note that P_0 is in the units of billions. you must also note that this will change what you want P(t) to end up being as well.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Junior Member
    Joined
    Oct 2008
    Posts
    68
    Quote Originally Posted by Jhevon View Post
    yes, if you note that P_0 is in the units of billions. you must also note that this will change what you want P(t) to end up being as well.
    Is the answer around 632 years?
    Follow Math Help Forum on Facebook and Google+

  8. #8
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by dc52789 View Post
    Is the answer around 632 years?
    nope, i got 817
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Junior Member
    Joined
    Oct 2008
    Posts
    68
    Quote Originally Posted by Jhevon View Post
    nope, i got 817
    How did you get 817?
    Follow Math Help Forum on Facebook and Google+

  10. #10
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by dc52789 View Post
    How did you get 817?
    1.68 \times 10^{14} = 6.3 \times 10^9e^{0.0125t} and solve for t
    Follow Math Help Forum on Facebook and Google+

  11. #11
    Junior Member
    Joined
    Oct 2008
    Posts
    68
    Quote Originally Posted by Jhevon View Post
    1.68 \times 10^{14} = 6.3 \times 10^9e^{0.0125t} and solve for t
    now I got it.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Population
    Posted in the Differential Equations Forum
    Replies: 4
    Last Post: March 12th 2011, 11:51 AM
  2. The population..
    Posted in the Calculus Forum
    Replies: 0
    Last Post: October 29th 2009, 10:46 AM
  3. Population
    Posted in the Calculus Forum
    Replies: 0
    Last Post: October 17th 2009, 11:33 AM
  4. population
    Posted in the Differential Equations Forum
    Replies: 2
    Last Post: February 9th 2009, 01:20 PM
  5. Population
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 23rd 2008, 04:48 PM

Search Tags


/mathhelpforum @mathhelpforum