Question

The annual Gross Domestic Product (GDP) of a country is the value of all of the goods and services produced in the country during a year. During the period 1985-1999, the Gross Domestic Product of the United States grew about 3.2% per year, measured in 1996 dollars. In 1985, the GDP was $577 billion. I what year did/or will the GDP equal $4.0 trillion?

Answer 1

GDP was a linear function of time (year) during the period of 1985-99.
The slope is positive.
Equation is: GDP(y)=(y-1985)*0.032*577+577=577*[(y-1985)*0.032+1] check: if y=1985, then GDP=577 .
So, we need to solve for "y" this equation: GDP=4000=577*[(y-1985)*0.032+1]then, y=[4000/577-1]/0.032+1985 =  2170.4 
we solveGDP=2200=577*[(y-1985)*0.032+1]  [4 is replaced by 2.2] y=[2200/577-1]/0.032+1985=2072.9  [almost 2073]