Question

Population of Timbaktoo (2 years ago) is 125000. Due to natural calamities people started migrating. So, population decreased at the rate of 4% per annum. How many migrated from his town in past 2 years?

• A. 98000
• B. 96000
• C. 9600
• D. 9800

Hint:

When a population decreases by \(r\%\) yearly for \(n\) years, multiply by \((1-r)^{n}\). The difference from the initial value is the total outflow.

Answer 1

The Correct Option is D

Step 1: Compute present population after 2 years of 4% fall p.a.
\[ P_{\text{now}} = 125000 \times (1-0.04)^2 = 125000 \times (0.96)^2 = 125000 \times 0.9216 = 115200. \] Step 2: Migrated (net decrease) in 2 years.
\[ \text{Migrated} = 125000 - 115200 = \boxed{9800}. \]