ap calculus

suppose that the amount in grams of a radioactive substance present at time t (in years) is given by A (t) = 160e-.70t. Find the rate of decay of the quantity present at the time when t = 4

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  1. A ' (t) = -.7(160) e^(-.7t)

    so A ' (4) = -.7(160) e^-2.8
    = -6.81

    insert the units

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