SOLUTION: the net amount of e-book sales in millions of dollars can be estimated by S(t)=2.05(1.8)^t, where t is the number of years after 2002. a) In what year was there $8 billion in e

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: the net amount of e-book sales in millions of dollars can be estimated by S(t)=2.05(1.8)^t, where t is the number of years after 2002. a) In what year was there $8 billion in e      Log On


   

Question 1117857: the net amount of e-book sales in millions of dollars can be estimated by S(t)=2.05(1.8)^t, where t is the number of years after 2002.
a) In what year was there $8 billion in e-book net sales?
b) Find the doubling time.
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
8=2.05%281.8%29%5Et

1.8%5Et=8%2F2.05

1.8%5Et=3.90243

t%2Alog%28%281.8%29%29=log%28%283.90243%29%29

t=log%28%283.90243%29%29%2Flog%28%281.8%29%29

t=2.316
This would be between or in years 2004

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1.8%5Et=2
t%2Alog%28%281.8%29%29=log%28%282%29%29
t=log%28%282%29%29%2Flog%28%281.8%29%29