Question

The population of a city increases by 10% every year. Its present population is
3.02,500. What was its population 2 years ago ?
(2018)
(1) 2,80,000 (2) 2,48,000 (3) 2,75,000 (4) 2,50,000
3​

Answer 1

Given:

• Present population of city is 302500
• Population of city is increasing 10% every year.

To find:

• Population of city before 2 years.

Solution:

Here, given that present population of city is 302500 and are increasing 10% per year.

We have to find population of city of before 2 year.

• Let suppose that population of city before two year was x

So, we have supposed that population of city was x.

Increased population of city in first year :

As given that population of city is increasing 10% per year.

=> 110% of x

=> $\dfrac{110x}{100}$

=> 1.1x

So, the population of city increased 1.1x in first year.

Increased population of city in second year :

110% of 1.1x

=> 110 × 1.1x/ 100

=> 121x/100

=> 1.21x

So, the population of city increased in second year was 1.21x

• So, population of city after 2 is 1.21x

Now,

Given that present population of city is 302500 and 1.21x

Let compare both quantity :

1.21x = 302500

=> x = 302500/1.21

=> x = 30250000/121

=> x = 250000

Therefore,

• Population of city before 2 year was 250000 (4th option)