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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.

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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?

Sum
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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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Chapter 14: Compound Interest - Exercise 14.4 [Page 27]

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R.D. Sharma Mathematics [English] Class 8
Chapter 14 Compound Interest
Exercise 14.4 | Q 10 | Page 27

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