yearly sales of DVD players s(t) (millions of dollars), t years after 1997 can be estimated by s(t)=200 * 2^t?

Question

then the book asked me to 1) determine the year which dvd sales will reach 2,800 million
so I just put log 2800 = 200 * 2^t then so log 2800/log200=2^t and then that equaled 3.0852357..=2^t and then I divided log 2 from 3.0852357 so it equaled 4.9 so that would be 2001 about, right?

and then it asked b)what is the doubling time for sales of dvd players and how do I figure that?

Answer 1

1)
Your solution is not correct. When you take log on both sides, you get
log(2800) = log(200) + t log(2) => t = [log(2800) - log(200)] / log(2).
It is better to do it as under.
2800 = 200 * 2^t
=> 1400 = 2^t
=> t = log(1400) / log2 = 10.45
=> year in which dvd sale will reach 2800 million $ is 2008.

b)
Sale is 200 at t = 0
Suppose it becomes 400 at time t = t
=> 400 = 200 * 2^t
=> 2 = 2^t
=> t = 1 year

Answer 2

a)
200 * 2^t = 2,800
2^t = 14
t * ln(2) = ln(14)
t = ln(14) / ln(2)
t ≈ 3.8073549220576041074419693172318
1997 + 4 = 2001
which accidentally matches your final answer.

b)
200 * 2^t = 400
2^t = 2
t = 1 year

Answer 3

Maxwell replaced into shrunk to Mumbai Indians for $7,761,seven hundred funds, so he's already over the mark. Assuming of direction which you calculate the quantity in Hong Kong funds. :-).