Results 1 to 3 of 3

Math Help - Bacteria Decay Help, Thank You in Advance

  1. #1
    Newbie
    Joined
    Oct 2009
    Posts
    4

    Bacteria Decay Help, Thank You in Advance

    A bacteria culture starts with 140 bacteria and grows at a rate proportional to its size. After 5 hours there will be 700 bacteria.

    Express the population after t hours as a function of t.
    population:


    I just don't really understand the wording and how it might look.
    Thank you,
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,888
    Thanks
    682
    Quote Originally Posted by alexiri33 View Post
    A bacteria culture starts with 140 bacteria and grows at a rate proportional to its size. After 5 hours there will be 700 bacteria.

    Express the population after t hours as a function of t.
    population:


    I just don't really understand the wording and how it might look.
    Thank you,
    since \frac{dP}{dt} = kP ...

    P = P_0 e^{kt}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Oct 2009
    From
    Brisbane
    Posts
    311
    Thanks
    2
    Quote Originally Posted by alexiri33 View Post
    A bacteria culture starts with 140 bacteria and grows at a rate proportional to its size. After 5 hours there will be 700 bacteria.

    Express the population after t hours as a function of t.
    population:


    I just don't really understand the wording and how it might look.
    Thank you,
    Any quantity which "grows at a rate proportional to its size" can be modelled exponentially as N = No x e^(kt)
    where the variables are : N is the quantity and t is time.
    No is the original quantity and k ic called the "Proportionality constant".

    In your case your equation is N = 140 x e^(kt).
    Now use the given fact (when t=5, N= 700) to find k.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Decay of a Decay. Is the diff eqn correct
    Posted in the Differential Equations Forum
    Replies: 2
    Last Post: July 29th 2010, 02:40 AM
  2. Decay rates in exponential decay
    Posted in the Math Topics Forum
    Replies: 2
    Last Post: December 21st 2009, 06:20 AM
  3. Paying In Advance
    Posted in the Business Math Forum
    Replies: 2
    Last Post: October 16th 2009, 10:50 AM
  4. Advance Functions. Must See!
    Posted in the Calculus Forum
    Replies: 2
    Last Post: April 17th 2009, 08:36 AM
  5. Discrete!! Please Help. thanks in advance
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: March 25th 2008, 09:23 AM

Search Tags


/mathhelpforum @mathhelpforum