SSC CGL 2025 Tier-I · 14 September 2025, Shift 2 · Quantitative Aptitude · Question 13 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.

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.

A certain amount grows to ₹6400 in 2 years and ₹7040 in 3 years. Determine the interest rate.

(a)10%
(b)9%
(c)8%
(d)11%

Answer

Why

Correct — A.
Growth from year 2 to year 3 = 7040 − 6400 = ₹640
With compound interest, that year's interest is earned on the year-2 amount, ₹6400.

Rate = 640 ÷ 6400 × 100 = 10%
Check: 6400 × 1.10 = 7040 → option (a).

Why the others are wrong

(b)
9% — 9% grows ₹6400 to ₹6976, not ₹7040. 9% is roughly 640 ÷ 7040, which puts the later amount in the denominator instead of the amount the interest was earned on.
(c)
8% — 8% grows ₹6400 to ₹6912 in the third year, ₹128 short of ₹7040. The year's gain of ₹640 is 10% of ₹6400.
(d)
11% — 11% overshoots: 6400 × 1.11 = ₹7104, which is ₹64 more than the ₹7040 the stem gives.

Concept

Under compound interest, each year's interest is earned on the amount at the start of that year. So the growth between two consecutive years, divided by the earlier amount, is the rate.

Here the growth from year 2 to year 3 is ₹640 on ₹6400, which is 10%. The principal is never needed.

Under simple interest the ₹640 would be added every year, putting the principal at ₹5120 and the rate at 12.5%.

The stem, as printed, does not say simple or compound interest. Read as simple interest, the same two amounts give 12.5%, which no option offers. The keyed 10% is the compound-interest reading.

Key facts

Compound interest: amount after n years = P(1 + r⁄100)ⁿ.
For consecutive years, rate = (next amount − earlier amount) ÷ earlier amount × 100.
Simple-interest amounts rise by the same rupee sum each year, not by the same percentage.

Study next

Finding the principal from two compound amounts: P = year-2 amount ÷ (1 + r⁄100)²Amounts two years apart at compound interest: their ratio is (1 + r⁄100)²Simple interest from two amounts: interest per year = difference ÷ gap in years

Common traps

Dividing ₹640 by ₹7040 instead of ₹6400, which gives about 9.1%.
Working it as simple interest and hunting for 12.5%.

15 Sep 2025, 16:00, Quant Q.10 asks the same with ₹12,000 and ₹13,200 at the end of years 2 and 3, and names compound interest: ₹1,200 on ₹12,000 is again 10%.

12 Sep 2025, 09:00, Quant Q.11 gives ₹6,600 and ₹7,920 at compound interest and asks for the principal instead.

Related PYQs

No directly related past PYQ was found.

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