Question:
The annual rate of growth in population of a certain city is 8%. If its present population is 196830, what it was 3 years ago?
Solution:
Population after three years $=\mathrm{P}\left(1+\frac{\mathrm{R}}{100}\right)^{\mathrm{n}}$
$196,830=\mathrm{P}\left(1+\frac{8}{100}\right)^{3}$
$196,830=\mathrm{P}(1.08)^{3}$
$\mathrm{P}=\frac{196,830}{1.259712}$
$=156,250$
Thus, the population three years ago was 156,250 .
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