SSC CGL 2025 Tier-I · 16 September 2025, Shift 1 · 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 13 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.

Two containers, A and B, contain mixtures of alcohol and water. Container A has alcohol and water in the ratio 4:1, while Container B has them in the ratio 5:2. If 10 liters are drawn from Container A and 14 liters from Container B, and the contents are mixed in a third container, what is the ratio of alcohol to water in the new mixture?

(a)3:1
(b)7:2
(c)9:4
(d)11:3

Answer

Why

Correct — A. Split each drawn quantity in its own container's ratio, then add like with like.

From A (4 : 1, so 5 parts): alcohol = 10 × 4⁄5 = 8 L, water = 10 × 1⁄5 = 2 L
From B (5 : 2, so 7 parts): alcohol = 14 × 5⁄7 = 10 L, water = 14 × 2⁄7 = 4 L

Total alcohol: 8 + 10 = 18 L
Total water: 2 + 4 = 6 L
Ratio 18 : 6 = 3 : 1 → option (a)

Why the others are wrong

(b)
7:2 — 7 : 2 makes water 2⁄9 of the mix, about 5.3 L of the 24 L. The two draws carry exactly 2 + 4 = 6 L of water, a quarter of the mix.
(c)
9:4 — 9 : 4 makes water 4⁄13 of the mix, about 7.4 L of the 24 L. The two draws carry only 2 L + 4 L = 6 L of water.
(d)
11:3 — 11 : 3 makes water 3⁄14 of the mix, about 5.1 L of the 24 L. The draws actually carry 6 L of water against 18 L of alcohol.

Concept

A quantity drawn from a well-mixed container carries that container's ratio. So 10 L of a 4 : 1 mixture is 8 L alcohol and 2 L water.

Ratios cannot be added directly. Convert each draw into litres of each liquid, add alcohol to alcohol and water to water, and only then form the new ratio.

Why adding the ratio terms seems to work here. 4 + 5 : 1 + 2 = 9 : 3 = 3 : 1 matches, but because each draw is exactly 2 × its ratio sum (10 = 2 × 5, 14 = 2 × 7).

Draw 7 L from B instead and the litres give 13 : 4, while the shortcut still says 3 : 1.

Key facts

A quantity drawn from a mixture in ratio a : b contains a⁄(a + b) of the first liquid.
Combine mixtures by adding actual quantities of each component, not by adding ratios.
Check a ratio against the total: 3 : 1 of 24 L is 18 L and 6 L, the amounts found.

Study next

Adding a pure component to change a mixture's ratioRemoving part of a mixture and replacing it with a pure componentAlligation for mixing two mixtures to reach a target ratio

Common traps

Adding the ratio terms (4 + 5 : 1 + 2) as a method — it matches here by coincidence and fails when the draws are not the same multiple of their ratio sums.
Splitting 10 L by 4 instead of by 4 + 1 = 5 parts, which gives 2.5 L a part instead of 2 L.

The drawn portion carrying its mixture's ratio also decides 13 Sep 2025, 12:30, Quant Q.14: 15 L removed from a 3 : 2 milk-water mix takes 9 L milk and 6 L water, and adding 10 L milk leaves 46 : 24 = 23 : 12.

10 Sep 2024, 16:00, Quant Q.11 compares two mixtures by each one's milk fraction: 10⁄16 and 8⁄12 give 15 : 16.

Related PYQs

No directly related past PYQ was found.

Topic: Mixture and Alligation — all 21 SSC CGL questions on it, every solved shift.