SSC CGL 2025 Tier-I · 18 September 2025, Shift 2 · Quantitative Aptitude · Question 7 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.

Reena borrowed Rs. 1200 at simple interest for a number of years equal to the rate of interest. At the end of the loan term, she paid Rs. 432 in interest. What was the interest rate?

(a)6%
(b)7%
(c)8%
(d)9%

Answer

Why

Correct — A. Use SI = P × R × T ⁄ 100 with T = R.

Substitute: 432 = 1200 × R × R ⁄ 100
Simplify: 432 = 12R²
Divide by 12: R² = 36
Take the square root: R = 6

So the rate is 6% a year, for 6 years → option (a).

Why the others are wrong

(b)
7% — 7% for 7 years gives 1200 × 7 × 7 ⁄ 100 = Rs. 588 of interest, not Rs. 432.
(c)
8% — 8% for 8 years gives 12 × 64 = Rs. 768 of interest, far above the Rs. 432 she paid.
(d)
9% — 9% for 9 years gives 12 × 81 = Rs. 972, more than double the Rs. 432 of interest.

Concept

Simple interest is P × R × T ⁄ 100. When the stem ties the time to the rate, the two unknowns become one: here T = R, so the formula becomes 1200 × R² ⁄ 100 = 12R².

That makes it a perfect-square question: 432 ÷ 12 = 36 = 6². With whole-number options, R² has to come out as a perfect square, so a messy quotient means an arithmetic slip.

The 36 that appears on the way is R × T, the total interest as a percentage of the principal (432 ⁄ 1200 = 36%). The rate is its square root, not 36% itself.

Key facts

Simple interest = P × R × T ⁄ 100, with R in % per annum and T in years.
When T = R, SI = P × R² ⁄ 100.
Rs. 1200 at 6% for 6 years earns 1200 × 36 ⁄ 100 = Rs. 432.

Study next

Simple interest where the rate is a multiple of the time, such as R = 5TFinding the rate when the interest is given as a fraction of the principalFinding the time when the amount, not the interest, is given

Common traps

Solving 432 = 12R as if the time were 1 year, which gives R = 36.
Reading 432 ⁄ 1200 = 0.36 as a 36% rate, when 36 is the rate multiplied by the time.

10 Sep 2024, 16:00, Quant Q.7 ties rate to time the same way: the rate is 5 times the years and the interest is one-fifth of the sum, so 5T² = 20, T = 2 and R = 10%.

It then raises the rate by 3%, read as 10% + 3% = 13%, and asks for the interest on ₹5,600 for 6 years: 5600 × 13 × 6 ⁄ 100 = 4368, the keyed answer.

Related PYQs

No directly related past PYQ was found.

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