The United States is the world’s largest
consumer of petroleum; China is second. In 2000, the United States
consumed 19.7 million barrels per day; this increased to 20.7 million
barrels per day by 2007. In 2000, China consumed 4.8 million barrels
per day; this increased to 7.6 million barrels per day by 2007.
Find exponential equations for the oil consumption of each country, where y is millions of barrels of petroleum per day and x is the year after 2000. Assume the yearly growth rate has been constant in each country.

Question

The United States is the world’s largest
consumer of petroleum; China is second. In 2000, the United States
consumed 19.7 million barrels per day; this increased to 20.7 million
barrels per day by 2007. In 2000, China consumed 4.8 million barrels
per day; this increased to 7.6 million barrels per day by 2007.
 Find exponential equations for the oil consumption of each country, where y is millions of barrels of petroleum per day and x is the year after 2000. Assume the yearly growth rate has been constant in each country.

phi · Answer

$$ y= Ae^{kt} $$
A is your initial value at time=0  (year 2000)
solve for k using the 2nd data point

anonymous · Answer

what is the answer exactly?

phi · Answer

I have not worked it out.

phi · Answer

I do notice they want you to use x  instead of t for years since 2000

phi · Answer

If you know y, A, and t, do you know how to solve for k?  (by taking the log of both sides?)

anonymous · Answer

no

phi · Answer

If you have time, this explains logs better than I can http://www.khanacademy.org/math/algebra/logarithms/v/introduction-to-logarithms