A super deadly strain of bacteria is causing the zombie population to double every day. Currently, t

Discussion in 'Calculator Requests' started by math_celebrity, Nov 4, 2019.

  1. math_celebrity

    math_celebrity Administrator Staff Member

    A super deadly strain of bacteria is causing the zombie population to double every day. Currently, there are 25 zombies. After how many days will there be over 25,000 zombies?

    We set up our exponential function where n is the number of days after today:
    Z(n) = 25 * 2^n

    We want to know n where Z(n) = 25,000.
    25 * 2^n = 25,000

    Divide each side of the equation by 25, to isolate 2^n:
    25 * 2^n / 25 = 25,000 / 25

    The 25's cancel on the left side, so we have:
    2^n = 1,000

    Take the natural log of each side to isolate n:
    Ln(2^n) = Ln(1000)

    There exists a logarithmic identity which states: Ln(a^n) = n * Ln(a). In this case, a = 2, so we have:
    n * Ln(2) = Ln(1,000)
    0.69315n = 6.9077

    Type this equation into our search engine, we get:
    n = 9.9657 days ~ 10 days
     

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