SOLUTION: I have never been good at word problems I am not sure how to solve or even write the equation to solve it. In 1975 the population of the Earth was approximately 4 billion and doub

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: I have never been good at word problems I am not sure how to solve or even write the equation to solve it. In 1975 the population of the Earth was approximately 4 billion and doub      Log On


   

Question 90069: I have never been good at word problems I am not sure how to solve or even write the equation to solve it.
In 1975 the population of the Earth was approximately 4 billion and doubling every 35 years. The formula for the population P in year Y for this doubling rate is
P (in billions)+250%2A2+%28y-1975%29%2F35+
The U.S. population in 1990 was approximately 250 million, and the average growth
rate for the past 30 years gives a doubling time of 66 years. The above formula for the
United States then becomes
P (in millions) +250+%2A+2%28+y-1990%29%2F66+
The question is : What will the population of the United States be in 2025 if this
growth rate continues?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The U.S. population in 1990 was approximately 250 million, and the average growth rate for the past 30 years gives a doubling time of 66 years. The above formula for theUnited States then becomes
P (in millions) =[ 250 * 2^[( y-1990)/66]]
The question is : What will the population of the United States be in 2025 if thisgrowth rate continues?
-------------
P(2025) = [250*2^[(2025-1990)/66]
P(2025) = [250*2^(35/66)]
P(2025) = [250*1.444232517]
P(2025) = [361.058... million]
==============
Cheers,
Stan H.