Question

The number of registered foreigners from Bangladesh increases by 10% every 2 years and that of unregistered foreigners from Bangladesh decreases by 10% every 2 years. If the total population of Afghanistan remain the same for all years and the number of foreigners from Bangladesh are 2% of the total population in 2012, then how many unregistered Bangladeshi were present in 2006. [In 2006, there were no foreigners in Afghanistan from any country except Bangladesh]

• A. 3 million
• B. 4 million
• C. 5 million
• D. 6 million

Answer 1

The correct option is D

6 million

Let registered foreigners and non-registered foreigners from Bangladesh in 2006 be x and y respectively.

Registered foreigners from Bangladesh in 2012 = 1.331x

Registered foreigners from Bangladesh in 2006 = x = $\frac{2.7\times 0.39}{1.331}$= 0.79 million

Let z be the total population.

0.79 + y = 0.025z ....(In 2006)

And 1.053 + 0.729y = 0.02z... (In 2012)

Solving for y, y = 5.9 million.