SSC CGL 2025 Tier-I · 12 September 2025, Shift 2 · Quantitative Aptitude · Question 9 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 13 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. The solutions are written by UnlockIAS.

Find the compound interest on ₹8,000 at 12% per annum for 3 years 4 months, compounded annually.

(a)₹3,000
(b)₹4,000
(c)₹3,689
(d)₹3,600

Answer

Why

Correct — C. Compound for the 3 full years, then add simple interest for the 4 months on the grown amount.

Year 1: 8,000 × 1.12 = 8,960
Year 2: 8,960 × 1.12 = 10,035.20
Year 3: 10,035.20 × 1.12 = 11,239.42

4 months: rate = 12% × 4⁄12 = 4%
11,239.42 × 1.04 = 11,689.00

CI = 11,689 − 8,000 = ₹3,689 → option (c)

Why the others are wrong

(a)
₹3,000 — ₹3,000 is less than the interest for the first 3 years alone, ₹3,239.42 (11,239.42 − 8,000). The extra 4 months can only add to that.
(b)
₹4,000 — The 3 full years earn ₹3,239.42, and the 4 months add 4% of ₹11,239.42, just ₹449.58. The total, ₹3,689, falls well short of ₹4,000.
(d)
₹3,600 — ₹3,600 would leave only about ₹361 for the 4 months, but 4% of ₹11,239.42 is ₹449.58. Charging the 4% on the grown amount gives ₹3,689.

Concept

With annual compounding, interest is added only at each year-end. For the part-year, the working that reaches the key charges simple interest on the amount at the end of the last full year, at the rate scaled to that fraction of a year.

As one formula: A = P(1 + r)³ × (1 + r × 4⁄12). Here 8,000 × 1.404928 × 1.04 = ₹11,689.00, so CI = ₹3,689.

Raising 1.12 to the power 10⁄3 instead, as if 3 years 4 months were a fractional exponent, gives about ₹3,672, which is not an option. The options and the key follow the part-year simple-interest method.

Key facts

For n full years at r% compounded annually, A = P(1 + r⁄100)ⁿ.
For a part-year under annual compounding, apply simple interest for that fraction on the last year-end amount.
1.12³ = 1.404928.

Study next

Compound interest compounded half-yearly or quarterlyDifference between compound and simple interest over 2 and 3 yearsFinding the rate or the time from a compound amount

Common traps

Stopping at 3 full years and dropping the 4 months, which gives ₹3,239.42.
Charging the 4 months at the full annual 12% instead of 12% × 4⁄12 = 4%.
Applying the 4% to the original ₹8,000 instead of the grown ₹11,239.42.

The same part-year method gives the key at 14 Sep 2025, 09:00, Quant Q.9 (₹10,000 at 10% for 2 years 6 months, CI ₹2,705) and 15 Sep 2025, 16:00, Quant Q.9 (₹7,000 at 9% for 1 year 8 months, CI ₹1,087.80).

Related PYQs

No directly related past PYQ was found.

Topic: Interest — all 82 SSC CGL questions on it, every solved shift.