exponential growth!!?

Question

The population of washington state increased from 4.86 million in 1990 to 5.89 million in 2000. Assuming exponential growth,

a. what will the population be in 2010?
b. what is the doubling time?

I'd appreciate any help.

Answer 1

a) 5.89/4.86=P2010./5.89
b)assume population grows over time P=Po exp(rt)
then log(P/Po)=rt or log(5.89/4.86)/10=r =.00834
population will double when exp (rt)=2 or rt=log 2=.301