9 February 2012, 6:05 pm
So the question is "Suppose the amount of oil pumped from one of the canyon wells in Whittier, California decrases at the continuous rate of 10% per year. When will the well's output fall to 60% of its present value?" We're using the equation y=C*e^(kt) Where C is the original amount, k is the rate of change, and t, in this problem, is measured in years. I think that k would come out to -.1 since it's a decay function and losing 10%. Here's how I tried to solve the equation. y=.60C .60C=C*e^(-.1*t) ln(.60) = ln(e^(-.1*t)) ln(.60) = -.1*t t=(ln(.60)/(-.1) = 5.10826 That seems like it would be right to me, and it's worked this way for the other equations I've done similar to this, but for some reason this one is incorrect. Does anyone know why?... Read More »
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