SOLUTION: how long will it take for the populations of a certain country to double if its annual growth rate is 6.2%?

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Question 722987: how long will it take for the populations of a certain country to double if its annual growth rate is 6.2%?
Found 2 solutions by stanbon, josmiceli:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
how long will it take for the populations of a certain country to double if its annual growth rate is 6.2%?
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The yearly multiplier is 1.0625
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Solve (1.0625)^k = 2
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k = log(2)/log(1.0625) = 11.43 years
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Cheers,
Stan H.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let P[n] = population after +n+ years
Let +P+ = the starting population
+r+ = rate of growth of population
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+P%5Bn%5D+=+P%2A%28+1+%2B+r+%29%5En+
given:
+2P+=+P%2A%28+1+%2B+.062+%29%5En+
+2+=++1.062%5En+
+log%282%29+=+n%2Alog%281.062%29+
+n+=+log%282%29+%2F+log%281.062%29+
+n+=+.30103+%2F+.02612+
+n+=+11.525+ yrs
+.525%2A12+=+6.3+
+.3%2A30+=+9+
It will take 11 years 6 months and 9 days