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Question
The population of a town increases at the rate of 40 per thousand annually. If the present population be 175760, what was the population three years ago.
Solution
Population after three years = P \[\left( 1 + \frac{R}{100} \right)^3 \]
\[175, 760 = P \left( 1 + \frac{40}{1000} \right)^3 \]
\[175, 760 = P \left( 1 . 04 \right)^3 \]
\[P = \frac{175, 760}{1 . 124864}\]
\[ = 156, 250\]
Thus, the population three years ago was 156, 250.
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