SSC CGL 2025 Tier-I · 15 September 2025, Shift 3 · 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 11 September 2026.

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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 ₹7,000 at 9% p.a. for 1 year 8 months, compounded annually.

(a)₹2,087.80
(b)₹1,000.80
(c)₹1,087.80
(d)₹2,000.80

Answer

Why

Correct — C. Compound for the whole year, then add simple interest on that amount for the 8 months.

After 1 year at 9%: 7,000 × 1.09 = ₹7,630
Rate for 8 months: 9% × 8⁄12 = 6%
Interest on ₹7,630 at 6%: 7,630 × 0.06 = ₹457.80

Amount: 7,630 + 457.80 = ₹8,087.80
Compound interest: 8,087.80 − 7,000 = ₹1,087.80 → option (c)

Why the others are wrong

(a)
₹2,087.80 — ₹2,087.80 is more than a full two years would earn: 7,000 × (1.09² − 1) = ₹1,316.70. Interest for 1 year 8 months cannot exceed that.
(b)
₹1,000.80 — ₹1,000.80 is less than the simple interest for the same period, 7,000 × 9% × 5⁄3 = ₹1,050. Compounding only adds to that, here by ₹37.80.
(d)
₹2,000.80 — ₹2,000.80 needs more than two full years at 9%, which earn only ₹1,316.70 on ₹7,000. The period here is 1 year 8 months.

Concept

By the standard convention for annual compounding, a part year earns simple interest on the amount already reached. The rate is scaled to the fraction of the year: 8 months is 8⁄12 of 9%, which is 6%.

So the amount is 7,000 × 1.09 × 1.06 = ₹8,087.80, and the interest is that minus the ₹7,000 principal.

Treating the time as a fractional power, 7,000 × 1.09^(5⁄3), gives about ₹1,081, which is not an option.

The key's ₹1,087.80 follows the whole-years-then-simple-interest convention above.

Key facts

Annual compounding for n whole years plus a fraction f of a year: A = P × (1 + R⁄100)ⁿ × (1 + fR⁄100).
8 months = 2⁄3 of a year, so a 9% annual rate becomes 6% for that part.
Over any period longer than a year, CI exceeds SI: here ₹1,087.80 against ₹1,050.

Study next

Compound interest with half-yearly and quarterly compoundingDifference between CI and SI for 2 and 3 yearsInterest earned in one particular year of a compound-interest loan

Common traps

Using 8% for the 8 months instead of 8⁄12 of 9% = 6%.
Charging the part-year interest on ₹7,000 instead of ₹7,630, which gives the simple interest of ₹1,050.

14 Sep 2025, 09:00, Quant Q.9 applies the same convention: ₹10,000 at 10% for 2 years 6 months is 10,000 × 1.1² × 1.05 = ₹12,705, so the interest is ₹2,705.

Related PYQs

No directly related past PYQ was found.

Topic: Interest — all 58 SSC CGL questions on it, every solved shift.