Compound Interest – Amount after half the time: If ₹ 3,000 becomes ₹ 4,329 at compound interest in a certain time, what will ₹ 3,000 amount to in half of that time (same rate, same compounding)?

Difficulty: Easy

Correct Answer: ₹ 3600

Explanation:

Introduction / Context:Compound growth over time is multiplicative. Knowing the full-period amount factor allows us to take the square root to get the half-period factor (for equal subperiods).

Given Data / Assumptions:

  • P = ₹ 3,000
  • Amount in full time = ₹ 4,329 → growth factor G = 4329/3000 = 1.443
  • Half the time → factor = √G

Concept / Approach:For equal halves of time at the same rate, the mid-time amount is P * √G.

Step-by-Step Solution:√1.443 ≈ 1.20125Amount at half time ≈ 3000 * 1.20125 = ₹ 3,603.75Closest listed option = ₹ 3,600

Verification / Alternative check:Squaring 1.20125 gives ≈ 1.443 (returns the full-period factor as required).

Why Other Options Are Wrong:₹ 3,520 and ₹ 3,400 are too low; ₹ 38,000 is clearly a typo/misfit.

Common Pitfalls:Halving the rupee interest from the full period instead of taking the square root of the factor.

Final Answer:₹ 3600

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