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Question
The population of a certain city was 72000 on the last day of the year 1998. During next year it increased by 7% but due to an epidemic it decreased by 10% in the following year. What was its population at the end of the year 2000?
Solution
Population at the end of the year 2000 = P \[\left( 1 + \frac{R_1}{100} \right)\left( 1 - \frac{R_2}{100} \right)\]
\[ = 72, 000\left( 1 + \frac{7}{100} \right)\left( 1 - \frac{10}{100} \right)\]
\[ = 72, 000\left( 1 . 07 \right)\left( 0 . 9 \right)\]
\[ = 69, 336\]
Thus, the population at the end of the year 2000 was 69, 336.
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