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The population of a town decreases 5% every year. If its present population is ₹ 216600. Find its population 2 years ago. - Mathematics

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Question

The population of a town decreases 5% every year. If its present population is ₹ 216600. Find its population 2 years ago.

Sum
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Solution

Given:

  • Present population = ₹ 216600.
  • The population decreases 5% every year.
  • We need to find the population 2 years ago.

Step-wise calculation:

1. Let the population 2 years ago be P.

2. Since the population decreases 5% each year, the population after 1 year would be `P xx (1 - 5/100) = P xx 0.95`.

3. Therefore, the population after 2 years the present population would be:

P × 0.95 × 0.95 = P × (0.95)2

4. Given the present population is 216600, we have:

216600 = P × (0.95)2

5. Solve for P:

`P = 216600/(0.95)^2`

`P = 216600/0.9025`

P = 240000

The population of the town 2 years ago was ₹ 240000.

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Chapter 2: Compound Interest - Exercise 2C [Page 53]

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Nootan Mathematics [English] Class 9 ICSE
Chapter 2 Compound Interest
Exercise 2C | Q 7. | Page 53
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