Okay. One last Exponential question?

Question

First the question:

Write a function expressing population in terms of the !number of years! that have elapsed since 1970;

The first part is done: P=203m(1.02)^t

Here is the whole question: The 1970 census showed that the population was about 203 million. The 1980 census showed that the population had grown to about 226 million.

So I think I have the function. I just dont know hoe to turn it around to reflent the number of years.

Please advise.

Thanx to all who have helped so far

Mike

Answer 1

not sure I agree with you

growth 1980 from 1970 (10 years) is 226/203
exp( ln(226/203)/10 ) = 1.010791

sp P = 203 * 1.010791^t
ln( P/203) = t ln 1.010791
so t = ( ln P - ln203) / ln 1.010791