Question

The annual rate of growth in population of a town is 5%. If its present population is 4000, what will be its population after 2 years? 

A. Rs. 4441 

B. Rs. 4400 

C. Rs. 4410 

D. Rs. 4800

Answer 1

Population of a town, P = 4000 

Time, n = 2 years 

Increasing rate, R = 5% per annum 

Now, 

Amount (A) = P (1 + R/100)ⁿ [Where, A = Amount with compound interest 

P = Present value 

R = Annual interest rate 

n = Time in years] 

∴ Population = P (1 + R/100)ⁿ 

= 4000 (1 + 5/100)² 

= 4000 (1 + 1/20)² 

= 4000 (21/20)² 

= 4000 × 21/20 × 21/20 

= 200 × 21 × 21/20 

= 10 × 21 × 21 

= 4410 

∴ Population of a town after 2 years is 4410.