document.write( "Question 885246: The count in a bateria culture was 600 after 20 minutes and 1600 after 30 minutes.\r
\n" ); document.write( "\n" ); document.write( "What was the initial size of the culture? \r
\n" ); document.write( "\n" ); document.write( "Find the doubling period. \r
\n" ); document.write( "\n" ); document.write( "Find the population after 90 minutes. \r
\n" ); document.write( "\n" ); document.write( "When will the population reach 11000
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Algebra.Com's Answer #535036 by josgarithmetic(39618)\"\" \"About 
You can put this solution on YOUR website!
You may be able to do this using hours instead of minutes.\r
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\n" ); document.write( "\n" ); document.write( "I = initial count of bacteria
\n" ); document.write( "p = count of bacteria after time t
\n" ); document.write( "\"highlight_green%28p=Ie%5E%28kt%29%29\", exponential growth formula\r
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\n" ); document.write( "\n" ); document.write( "Interesting that we do not know the count of bacteria at time t=0.\r
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\n" ); document.write( "\n" ); document.write( "\"ln%28p%29=ln%28Ie%5E%28kt%29%29\"
\n" ); document.write( "\"ln%28p%29=ln%28I%29%2Bln%28e%5E%28kt%29%29\"
\n" ); document.write( "\"ln%28p%29=ln%28I%29%2Bkt%2A1\"
\n" ); document.write( "\"highlight_green%28ln%28p%29=ln%28I%29%2Bkt%29\", a LINEAR equation. The vertical axis intercept is \"ln%28I%29\" and the slope is \"k\". The vertical axis variable is \"ln%28p%29\" and is a function of time \"t\".\r
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\n" ); document.write( "\n" ); document.write( "You have two data points to help in getting vertical intercept and slope.
\n" ); document.write( "20 & 600;
\n" ); document.write( "30 & 1600.
\n" ); document.write( "The way you must use them first is this way:
\n" ); document.write( "20 & ln(600)=6.3969
\n" ); document.write( "30 & ln(1600)=7.3778
\n" ); document.write( "Meaning the two points for the LINEAR form of this description are these:
\n" ); document.write( "(20, 6.3969) and (30, 7.3778).
\n" ); document.write( "-
\n" ); document.write( "k or SLOPE
\n" ); document.write( "\"k=%287.3778-6.3969%29%2F%2830-20%29\"
\n" ); document.write( "\"k=0.9809%2F10\"
\n" ); document.write( "\"k=0.09809\"
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\n" ); document.write( "Vertical Intercept
\n" ); document.write( "\"ln%28p%29=ln%28I%29%2Bkt\"
\n" ); document.write( "\"ln%28I%29=ln%28p%29-kt\"
\n" ); document.write( "Pick either point to finish finding ln(I).
\n" ); document.write( "\"ln%28I%29=7.3778-0.09809%2A30\"
\n" ); document.write( "\"ln%28I%29=4.4351\"
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\n" ); document.write( "Antilog, base e, for 4.4351 will be I.
\n" ); document.write( "\"I=84\", more sensible than saying 84.36...
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\n" ); document.write( "Build back the exponential growth equation using the now found values:
\n" ); document.write( "\"highlight%28p=84%2Ae%5E%280.09809t%29%29\".
\n" ); document.write( "You can answer whatever questions you want for this fictional or factual bacteria culture.\r
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\n" ); document.write( "\n" ); document.write( "Find the doubling period.
\n" ); document.write( "Just let I=1 and p=2. Now find t.\r
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\n" ); document.write( "\n" ); document.write( "Find the population after 90 minutes.
\n" ); document.write( "Obviously, just let t=90...\r
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\n" ); document.write( "\n" ); document.write( "When will the population reach 11000
\n" ); document.write( "Let p=11000 and solve for t. There are clues how to do these i some of the steps I showed.
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