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Math Help - doubling period question....

  1. #1
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    doubling period question....

    The doubling period of a baterial population is minutes. At time minutes, the baterial population was 60000. With representing minutes, the formula for the population is .

    1. ????
    2. The initial population at time is???
    3. The size of the baterial population after 3 hours is???


    i've been trying to plug in and guess, but it's just not working...!!!!!
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  2. #2
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    Quote Originally Posted by badshahkhan View Post
    The doubling period of a baterial population is minutes. At time minutes, the baterial population was 60000. With representing minutes, the formula for the population is .

    1. ????
    2. The initial population at time is???
    3. The size of the baterial population after 3 hours is???


    i've been trying to plug in and guess, but it's just not working...!!!!!
    60000 = Ae^{80k}

    30000 = Ae^{65k}

    divide the 1st equation by the 2nd one ...

    2 = e^{15k}

    solve for k ... then determine A ... then find P(180)<br />
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  3. #3
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    i put .692/15 and got .046 but that does not seem to be the right value for K
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  4. #4
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    Quote Originally Posted by badshahkhan View Post
    i put .692/15 and got .046 but that does not seem to be the right value for K
    why not ?
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  5. #5
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    Quote Originally Posted by skeeter View Post
    why not ?

    because when i enter this into the system where I have to submit the answer, it prompts me by saying incorrect....
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  6. #6
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    Quote Originally Posted by badshahkhan View Post
    because when i enter this into the system where I have to submit the answer, it prompts me by saying incorrect....
    well ... I can guarantee that the exponential constant, k , for any doubling period is \frac{\ln(2)}{t} , where t is the doubling period.

    \frac{\ln(2)}{15} = 0.046209812...

    sorry that the online answering system doesn't recognize it.
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  7. #7
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    i take that back, i needed to enter one more decimal..i was rounding it
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