The population of a small city decreased every year due to water contamination. The present population of the town is 1,39,650. Last year, the migration was 2%, and the year before last, it was 5%. What was the population of the city two years ago?

Correct option is B

Given:

Present population = 1,39,650

Migration last year = 2%

Migration year before last = 5%

Formula used:

Population after decrease = Previous population × (1 - Decrease rate)

Solutions:

Let the population two years ago be P.

Population after 1st year decrease = P × $$\left(1 -\frac 5{100}\right)$$​​

Population after 1st year = P × 0.95

Population after 2nd year decrease = (P × 0.95) × $$\left(1 -\frac 2{100}\right)$$​​

Population after 2nd year = P × 0.95 × 0.98

We know that population after 2nd year = 1,39,650.

1,39,650 = P × 0.95 × 0.98

P = $$\frac{1,39,650 }{ (0.95 × 0.98)}$$ 

P = 1, 50 ,000

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