SSC CGL 2025 Tier-I · 14 September 2025, Shift 2 · Quantitative Aptitude · Question 12 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.

Rohan ordered 5 kg of premium coffee and some additional kilograms of ordinary coffee. The price of the premium coffee per kg was three times that of the ordinary coffee. When the order was delivered, it was found that the quantities of premium and ordinary coffee had been swapped. This change increased his bill by 40%. Find the ratio of the original quantity of premium coffee to the original quantity of ordinary coffee.

(a)2 : 1
(b)1 : 3
(c)1 : 2
(d)3 : 1

Answer

Why

Correct — C.
Let ordinary coffee cost p a kg, so premium costs 3p.
Let the ordinary coffee ordered be x kg.

Original bill = 5 × 3p + x × p = (15 + x)p
Swapped bill = x × 3p + 5 × p = (3x + 5)p

A 40% rise means swapped = 1.4 × original:
3x + 5 = 1.4(15 + x) = 21 + 1.4x
1.6x = 16, so x = 10 kg

Premium : ordinary = 5 : 10 = 1 : 2 → option (c).

Why the others are wrong

(a)
2 : 1 — 2 : 1 is the ratio upside down, ordinary to premium. With 5 kg premium and 2.5 kg ordinary, the swap cuts the bill from 17.5p to 12.5p instead of raising it.
(b)
1 : 3 — 1 : 3 raises the bill too far. With 5 kg premium and 15 kg ordinary, the bill goes from 30p to 50p, a rise of 66.7%, not 40%.
(d)
3 : 1 — 3 : 1 gives a 40% fall, not a rise. With 5 kg premium and 5⁄3 kg ordinary, the bill drops from about 16.67p to 10p, but the stem says the swap increased it.

Concept

Swapping two quantities while their prices stay fixed changes the bill because the dearer coffee now comes in the other amount. For the swap to raise the bill, the dearer coffee must have been ordered in the smaller amount.

Write each bill with one unknown quantity and one unit price, then turn the percentage change into an equation.

Check: the original bill is 15p + 10p = 25p, the swapped bill is 30p + 5p = 35p, and 10p on 25p is exactly 40%.

Key facts

An increase of 40% means new value = 1.4 × old value.
The unit price p cancels from both sides, so the answer does not depend on the actual price.
If the dearer item is the smaller quantity, swapping raises the bill. If it is the larger quantity, swapping lowers it.

Study next

Interchanged quantities with a given change in total, such as notes of two denominationsPrice per kg of a blend of two varietiesForming a linear equation from a percentage change

Common traps

Reporting ordinary : premium, 2 : 1, when the stem asks premium : ordinary.
Treating the 40% as a fall, which leads to x = 5⁄3 kg and a ratio of 3 : 1.

23 Sep 2024, 09:00, Quant Q.9 interchanges ₹20 and ₹10 notes: a total of ₹390 that falls by ₹90 after the swap fixes 16 notes of ₹20.

15 Sep 2025, 12:30, Quant Q.8 interchanges two loan principals at 9% and 6% simple interest, where the swap would cut four years' interest by ₹1,200.

Related PYQs

No directly related past PYQ was found.

Topic: Ratio & Proportion — all 64 SSC CGL questions on it, every solved shift.