1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Bacteria Growth Problem.

  1. May 11, 2005 #1
    My friend had to do this problem in Calculus BC. I'm no good at calculus, but I decided it was be fun for someone to figure it out for me.

    A bacteria culture starts with 500 bacteria and grows at a rate proportional to its size. After 3 hours there are 8000 bacteria.
    (a) Find an expression for the number of bacteria after t hours.
    (b) Find the number of bacteria after 4 hours.
    (c) Find the rate of growth after 4 hours.
    (d) When will the population reach 30,000?

    I think it involves differential equations.
  2. jcsd
  3. May 11, 2005 #2
    :rofl: :rofl: :rofl:

    Start with [tex]y=Ae^{kt}[/tex]
  4. May 11, 2005 #3
    Yeah that amused me too :smile: .I'd probably start a little earlier:

    Growth proportional to size implies.....


    with the intial condition [tex]y(0)=500[/tex] and the time t = 3 (in hours!) condition [tex]y(3)=8000[/tex].

    Your mission, should you choose to accept it, is to find the general solution to the DE above, and the values of k and the constant of integration A.

    That's the model, the rest should be ok?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Bacteria Growth Problem.
  1. Bacteria growth rate (Replies: 4)

  2. Population Growth (Replies: 8)