Question

the population of a city is 20000.It increase at the rate of 5% per annum.Find the population after 3 years​

Answer 1

Your Answer:

Given:-

• population of city = 20000
• rate of increase = 5 % per annum

To find:-

• the population of city after 3 years

Solution:-

$\large \tt A=P(1+\frac{R}{100})^{n}$

Here,

A= population after 3 years

P= current population(that is 20000)

R= 5%

n= 3 years

$\large \tt A=P(1+\frac{R}{100})^{n} \\ \\ =20000(1+\frac{5}{100})^{3}\\\\=20000(1+\frac{1}{20})^{3}\\\\=20000(\frac{21}{20})^{3}\\\\=20000(\frac{21\times21\times21}{20\times20\times20})\\\\=2.5\times21\times21\times21\\\\=23152.5$

But, population can not be in decimals So, 23153 is the population.