SSC CGL 2024 Tier-I · 18 September 2024, Shift 1 · Quantitative Aptitude · Question 15 of 99

Text as printed on a candidate's response sheet for this shift; answer per SSC's tentative key as marked on that sheet. Solution last reviewed 6 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. The questions and options here are reproduced as printed on a candidate's own response sheet for this shift — the Commission's text, unchanged. Each answer is SSC's tentative key as marked on that sheet; SSC allowed challenges to it and never publishes a final key. The solutions are written by UnlockIAS.

A certain sum of money is given at a certain rate of simple interest for 6 years. Had it been given at 7% higher rate, it would have fetched ₹1,512 more. Find the sum (in ₹).

(a)3,600
(b)3,100
(c)3,200
(d)4,200

Answer

Why

Correct — A. Only the rate changes. The sum and the 6 years are the same in both cases, so the extra ₹1,512 is simply the interest earned by the extra 7%.

extra SI = P × 7 × 6 ⁄ 100 = 1512

42P ⁄ 100 = 1512
P = 1512 × 100 ⁄ 42

P = 3,600 → option (a)

The original rate never enters the working, which is why the stem can leave it as 'a certain rate'.

Why the others are wrong

(b)
3,100 — ₹3,100 would earn 3100 × 42⁄100 = ₹1,302 of extra interest over the six years — ₹210 short of the ₹1,512 given.
(c)
3,200 — ₹3,200 gives 3200 × 42⁄100 = ₹1,344 of extra interest, still below the stated ₹1,512.
(d)
4,200 — ₹4,200 overshoots: 4200 × 42⁄100 = ₹1,764. It is the answer only if the multiplier is taken as 36% instead of the 6 × 7 = 42% the stem sets up.

Concept

Simple interest is SI = P × R × T ⁄ 100, and because it is linear in R, changing the rate by ΔR changes the interest by exactly P × ΔR × T ⁄ 100.

The unknown original rate cancels out of that difference. That is the whole design of this question type: you are handed ΔR and the change in interest, and asked for P.

Compound interest does not allow the same move — there the two rates do not separate, and the original rate has to be known.

'7% higher rate' means 7 percentage points added to the annual rate, not a 7% increase on the existing rate.

The two readings give different answers, and only the first one lets the unknown original rate cancel — which is what makes the question solvable at all.

Key facts

SI = P × R × T ⁄ 100, linear in each of P, R and T.
A rate rise of 7 percentage points over 6 years adds 42% of the principal to the interest, whatever the original rate was.
Here 42% of P = ₹1,512, so P = ₹3,600.

Study next

Difference-of-simple-interest items where the time, not the rate, changesFinding the rate when SI is given as a fraction of the principalWhy the rate-difference shortcut fails under compound interest

Common traps

Hunting for the original rate, which the stem never supplies and the working never needs
Taking 7% of the interest instead of 7% per annum of the principal
Using 7% as the multiplier and forgetting to multiply by the 6 years

SSC's simple-interest slot rotates between finding P, R, T and a difference.

A difference item that hands you the principal and moves both the rate and the time — the reverse of this one — is at 23 Sep 2024, 09:00, Quant Q.8, and an SI-as-a-fraction-of-the-sum item at 25 Sep 2024, 09:00, Quant Q.13.

Related PYQs

No directly related past PYQ was found.