Question

In Afghanistan, registered foreigners increased by 10% every 2 years. In 2008, 40% of the foreigners were unregistered. What was the total population of Afghanistan in 2008?

• A. 180.4 million
• B. 123 million
• C. 96 million
• D. 82 million

Answer 1

The correct option is B 123 million

The number of registered foreigners in 2012 is 1.21 times $(1.1{)}^2$ the number of registered foreiners in 2008 (as the their number increases 10% every 2 years)

So, registered foreigners in 2008 = $\left(\frac{2.7}{121}\right)\times 100$= 2.23 million

Therefore total foreigners in 2008 = $\left(\frac{2.23}{60}\right)\times 100$= 3.7 million

So, total population of Afghanistan in 2008 = $\left(\frac{3.7}{3}\right)\times 100$= 123 million.