Question

The population of a town 2 years ago was 62500. Since some people migrate to different cities the number of people decreases every year at the rate of 4% per annum. Find its present population. [4 MARKS]

Answer 1

Formula: 1 Mark
Application: 1 Mark
Steps: 1 Mark
Answer: 1 Mark

Given that,

Population 2 years ago = 62500.

Rate of decrease = 4 % p.a.

For population 1 year ago,

P = 62500 , R = 4 %, T = 1 year

$\therefore S.I=\frac{P\times R\times T}{100}$

$\Rightarrow I=\frac{62500\times 4\times 1}{100}$

$\Rightarrow I=2500$

$\Rightarrow$ After 1 year the population will decrease by 2500 people

$\therefore$ Population 1 year ago is = 62500 - 2500 = 60,000

For present population,

P = 60,000, R = 4 %, T = 1 year

$\therefore S.I=\frac{P\times R\times T}{100}$

$\Rightarrow I=\frac{60000\times 4\times 1}{100}$

$\Rightarrow I=2400$

$\Rightarrow$ Present population = 60,000 - 2400 = 57,600

[We are subtracting the population because population is decreasing by 4% p.a.]
The present population is 57,600.