SSC CGL 2024 Tier-I · 19 September 2024, Shift 1 · Quantitative Aptitude · Question 1 of 100

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 10 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 vendor started selling vegetables at ₹10 per kg, but couldn’t find buyers at this rate. So he reduced the price to ₹7.2 per kg, but uses a faulty weight of 900 g instead of 1 kg. Find the percentage change in the actual price.

(a)10%
(b)15%
(c)25%
(d)20%

Answer

Why

Correct — D. Compare both rates on a genuine kilogram.

Old rate = ₹10 per real kg

New rate = ₹7.2, but the buyer receives only 900 g
True new rate = 7.2 ⁄ 0.9 = ₹8 per real kg

Fall = 10 − 8 = ₹2, taken on the original ₹10
= 2 ⁄ 10 × 100 = 20% decrease → option (d)

Why the others are wrong

(a)
10% — 10% is the shortfall in the weight (100 g missing from every kilogram), not the change in price. The weight error feeds into the rate calculation, it is not the answer to it.
(b)
15% — No step here produces 15%. It sits between the two tempting wrong answers and survives only as a guess, since neither ₹7.2 nor ₹8 stands in a 15% relation to ₹10.
(c)
25% — 25% is the ₹2 fall divided by the new ₹8 instead of the original ₹10. Percentage change is always measured on the figure you started from.

Concept

Two separate things move in this sale: the quoted rate and the quantity actually handed over.

A vendor who bills 900 g as a kilogram is charging ₹7.2 for 0.9 kg. Restated per genuine kilogram, that is 7.2 ⁄ 0.9 = ₹8.

Convert both rates to the same real unit before comparing them. Only then does percentage change mean anything, and it is computed on the original value, ₹10.

'Actual price' in this question means the price of a real kilogram, not the ₹7.2 written on the board. That is the whole trick: the reduction looks like 28% and is really 20%.

Key facts

A faulty 900 g weight means the true rate per kilogram is the quoted rate divided by 0.9.
₹7.2 charged for 900 g works out to ₹8 per genuine kilogram.
Percentage change divides by the original value, so (10 − 8) ⁄ 10 = 20%.

Study next

False-weight problems where a shopkeeper discounts and short-weighs at the same timeChoosing the correct base for percentage increase against percentage decreaseEffective rate per unit when both price and quantity are altered

Common traps

Dividing the ₹2 fall by the new ₹8, which returns 25%.
Ignoring the faulty weight and comparing ₹7.2 with ₹10 to get 28%.
Treating the 100 g shortage as a 10% price effect.

SSC writes these as an honest-looking price cut with the cheating weight buried in the last clause, so the reader who stops at the two rupee figures is already wrong. Percentage arithmetic on a shifted base also drives Quant Q.14 and Q.17 in this shift.

Related PYQs

No directly related past PYQ was found.