Question

The population of a town increases by 10% annually. If the present population is 22000, find its population a year ago.

Answer 1

Let the population of the town one year ago = x
Now, it is given that population of the town increases by 10 % annually.
Present population = x + 10 % of x
\[ = x + \frac{10}{100} \times x\]
\[ = x + \frac{x}{10}\]
\[ = \frac{11x}{10}\]
But present population of the town = 22000
So,\[ \frac{11x}{10} = 22000\]
\[ \Rightarrow 11x = 220000\]
\[ \Rightarrow x = \frac{220000}{11}\]
\[ \Rightarrow x = 20000\]
So, population of the town 1 year ago = 20000