Question

The population of a town increases annually by 25%. If the present population is 1 crore, then what is the difference between the population three years ago and 2 years ago?

(a) 25,00,000

(b) 12,80,000

(c) 15,60,000

(d) None of these

Answer 1

Correct option is (b) 12,80,000

Present population = 10000000

Let old population be x

Population one year ago = (x + x) of 25%

∴ (x + x) of 25% = 10000000

1.25x = 10000000

x = 8000000

Population two years ago = x + x of 25%

∴ (x + x) of 25% = 8000000

1.25x = 8000000

x = 6400000

Population of 3rd year ago = x + x of 25%

1.25x = 6400000

x = 5120000

Hence,

Difference between the population 3 years ago and 2 years ago = 6400000 – 5120000 = 1280000