document.write( "Question 685199: The popluation of Oregon grew from 2.8 million in 1980 to 3.42 million in 1990. Write a base-e exponential function to show how popluation depends on time. What population would be predicted for 2008? After how many years will Oregon's popluation double? \n" ); document.write( "
Algebra.Com's Answer #424467 by stanbon(75887)\"\" \"About 
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The popluation of Oregon grew from 2.8 million in 1980 to 3.42 million in 1990. Write a base-e exponential function to show how population depends on time.
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\n" ); document.write( "y = ae^(rt)\r
\n" ); document.write( "\n" ); document.write( "---
\n" ); document.write( "Using (0,2.8)
\n" ); document.write( "2.8 = ae^0
\n" ); document.write( "a = 2.8
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\n" ); document.write( "Using (10,3.42)
\n" ); document.write( "3.42 = 2.8e^(10r)
\n" ); document.write( "e^(10r) = 1.22
\n" ); document.write( "10r = ln(1.22)
\n" ); document.write( "r = 0.0199
\n" ); document.write( "-----
\n" ); document.write( "Equation:
\n" ); document.write( "y = 2.8e^(0.0199t)
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\n" ); document.write( "What population would be predicted for 2008?
\n" ); document.write( "f(8) = 2.8*e^(0.0199*8) = 3.28 million
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\n" ); document.write( "\n" ); document.write( "After how many years will Oregon's population double?
\n" ); document.write( "It doubles when e^(0.0199t) = 2
\n" ); document.write( "0.0199t = ln(2)
\n" ); document.write( "t = ln(2)/0.0199
\n" ); document.write( "t = 34.8 years
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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