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Homework Help: Volume of chlorine homework

  1. Mar 9, 2006 #1
    13 The volume of chlorine, C litres, in a swimming pool at time t hours after it was placed in
    the pool can be modelled by C(t) = C0e^kt, t ≥ 0. The volume of chlorine in the pool is
    decreasing. Initially the volume of chlorine in the pool was 3 litres, 8 hours later the
    volume was 2.5 litres.

    b Find the exact value of k.
    i tried to work this question out but it do not turned out to be right.
    i used C(t)=3e^kt
    where c(t)=3
    then there is another equation C(t)=2.5e^8t
    then i used simultanoeus equation
    is this method correct?

    thank you
  2. jcsd
  3. Mar 9, 2006 #2


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    Homework Helper

    This means C(0) = 3. Plug it in the expression for C(t), we have:
    C(t) = C(0)ekt = 3ekt, right?
    This means that C(8) = 3ek8 = 2.5
    From here, can you solve for k?
    By the way, this can be done exactly in the same way as this problem.
    Can you go from here? :)
  4. Mar 9, 2006 #3
    thank you
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