Simple Interest — Mr. Pawan invests ₹ 2,42,000 at 4% p.a. for 6 years (simple). He then invests the accumulated amount (principal + interest) for another 4 years at the same rate, again under simple interest. Find the simple interest earned in the last 4 years.

Difficulty: Medium

Correct Answer: ₹ 48,012.80

Explanation:


Introduction / Context:
This is a two-stage simple-interest investment. Stage 1 grows the principal linearly; Stage 2 uses that higher base (principal + first-stage interest) to earn further simple interest. The question specifically asks for the interest of the second stage only.



Given Data / Assumptions:

  • Initial principal P = ₹ 2,42,000.
  • Rate r = 4% p.a. throughout; simple interest only.
  • Stage 1 time t1 = 6 years; Stage 2 time t2 = 4 years.


Concept / Approach:
Stage 1 interest: SI1 = P * r * t1. Amount after Stage 1: A1 = P + SI1. Stage 2 interest on A1: SI2 = A1 * r * t2.



Step-by-Step Solution:
SI1 = 2,42,000 * 0.04 * 6 = ₹ 58,080.A1 = 2,42,000 + 58,080 = ₹ 3,00,080.SI2 = 3,00,080 * 0.04 * 4 = 3,00,080 * 0.16 = ₹ 48,012.80.



Verification / Alternative check:
Orderly separation of stages ensures no compounding is assumed; each segment is linear SI on its own base.



Why Other Options Are Wrong:
₹ 48,000 rounds off A1; ₹ 47,000 and ₹ 46,800 are underestimates; ₹ 48,501.28 uses an incorrect base or rate.



Common Pitfalls:
Accidentally compounding or taking Stage 2 interest on the original P; the correct base is A1.



Final Answer:
₹ 48,012.80

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