A town has 8000 people. The population increases by 10% in the first year and by 20% in the second year. What will be the population after 2 years?

Difficulty: Easy

Correct Answer: 10560

Explanation:


Introduction / Context:
Successive percentage changes compound multiplicatively. Apply each year’s growth factor to the running total rather than summing the percentages.


Given Data / Assumptions:

  • Initial population = 8000.
  • Year 1 growth = +10% ⇒ factor 1.10.
  • Year 2 growth = +20% ⇒ factor 1.20 applied to the result after year 1.


Concept / Approach:
Final population = 8000 * 1.10 * 1.20. Multiply the factors first or compute year by year; both yield the same result. This is standard compound percentage growth.


Step-by-Step Solution:

After Year 1: 8000 * 1.10 = 8800.After Year 2: 8800 * 1.20 = 10560.


Verification / Alternative check:
Combine factors: 1.10 * 1.20 = 1.32 ⇒ 8000 * 1.32 = 10560. Same answer.


Why Other Options Are Wrong:
10400 assumes adding percentages once (10% of 8000 plus 20% of 8000); 10620 is a mis-multiplication; “None of these” is not applicable.


Common Pitfalls:
Adding 10% and 20% to get 30% and then taking 30% of 8000 (2400) to claim 10400; that ignores compounding.


Final Answer:
10560

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