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Unformatted text preview: aul Dawkins 311 http://tutorial.math.lamar.edu/terms.aspx College Algebra Let’s do that. 10000 0.195 t
=e
500
20 = e0.195 t
ln 20 = ln e0.195 t
ln 20 = 0.195t Þ t= ln 20
= 15.3627
0.195 So, it only takes approximately 15.4 hours to reach 10000 bacteria and NOT 24 hours if we just
double the time from the first part. In other words, be careful!
[Return to Problems] Example 4 Carbon 14 dating works by measuring the amount of Carbon 14 (a radioactive
element) that is in a fossil. All living things have a constant level of Carbon 14 in them and once
they die it starts to decay according to the formula, Q = Q0e0.000124 t
where t is in years and Q0 is the amount of Carbon 14 present at death and for this example let’s
assume that there will be 100 milligrams present at death.
(a) How much Carbon 14 will there be after 1000 years? [Solution]
(b) How long will it take for half of the Carbon 14 to decay? [Solution]
Solution
(a) How much Carbon 14 will there be after 1000 years?
In this case all we need to do is plug in t=10...
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This note was uploaded on 06/06/2012 for the course ICT 4 taught by Professor Mrvinh during the Spring '12 term at Hanoi University of Technology.
 Spring '12
 MrVinh

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