SOLUTION: How would you go about finding when the percent of foreign ­born citizen was at its highest and when it was at its lowest percent since 1990? Info: The U.S. population that w

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Question 1036253: How would you go about finding when the percent of foreign ­born citizen was at its highest and when it was at its lowest percent since 1990?
Info:
The U.S. population that was foreign-born since 1900 can be modeled by
+p%28t%29+=+0.00006t%5E3+-+0.007t%5E2+%2B+0.05t+%2B+14+ where t = 0 in 1990.
Here is the graph of the polynomial function: http://postimg.org/image/hz7mo786z/
Answer by Aldorozos(172) About Me  (Show Source):
You can put this solution on YOUR website!
This is a calculus problem. I give you some guidelines and hope it helps
First use Google to familiarize yourself with maximum and minimum using derivatives: Here is an example
https://www.mathsisfun.com/calculus/maxima-minima.html
We have to find the derivative of p(t) which is 3(.00006t^2)-2(.007t)+.05
We set this derivative to zero since at maximum the derivative is supposed to be zero 3(.00006t^2)-2(.007t)+.05 = 0 This is a quadratic equation. To solve it manually we can multiply all sides of the equation by 100,000 to get ride of the decimals and we end up having 3t^2-1400t - 5000 = 0
If we solve this equation we may gat t as 478
Now we have to set the t in our original equation to calculate the Y. By original equation, I means p(t). Of course this problem requires some calculation using calculator.