Unformatted text preview: 20 / 20 = e − 1 times as salty as the original brine. 9. Let p ( t ) be the population of splake in the lake at time t . We start counting the population in 1980. Thus, we let t = 0 correspond to the year 1980. By the Malthusian law stated on page 93 of the text, we have p ( t ) = p e kt . Since p = p (0) = 1000, we see that p ( t ) = 1000 e kt . To Fnd k we use the fact that the population of splake was 3000 in 1987. Therefore, p (7) = 3000 = 1000 e k · 7 ⇒ 3 = e k · 7 ⇒ k = ln 3 7 . 108...
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 Spring '10
 Hald,OH
 Math, Differential Equations, Linear Algebra, Algebra, Equations, Optimization, Elementary algebra, Thomas Robert Malthus

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