Precalculus : Application Problems
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Example Questions
Example Question #11 : Application Problems
The exponential decay of an element is given by the function
where 
To solve for the initial amount, we must use rearrange the equation:
We now substitute the values given from the problem
Example Question #12 : Application Problems
There were 240mg of caffeine in the discontinued energy drink. The decay rate for caffeine in the human bloodstream is around 0.14. If Jackie drinks this energy drink around 8PM, how much caffeine will still be in her system at midnight?
Because this is a process taking place in the human body, we should use the exponential decay formula involving e:
where A is the current amount, P is the initial amount, r is the rate of growth/decay, and t is time.
In this case, since the amount of caffeine is decreasing rather than increasing, use 
Now evaluate:
Example Question #1124 : Algebra
Stuff animals were a strange craze of the 90's. A Cat stuff animal with white paws sold for $6 in 1997. In 2015, the Cat will sell for $1015. What has been the approximate rate of growth for these stuff animal felines?
Use the formula for exponential growth 
Our equation is now:
As a percent, r is about 33%.
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