SSC CGL 2025 Tier-I · 17 September 2025, Shift 1 · General Intelligence and Reasoning · Question 22 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.

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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.

A 30 L mixture contains milk and water in the ratio 3:2. How much milk must be added to make it 4:1?

(a)51 L
(b)60 L
(c)30 L
(d)40 L

Answer

Why

Correct — C.
Rule: the liquid you do not add stays fixed, here the water.

Milk = 3⁄5 × 30 = 18 L
Water = 30 − 18 = 12 L
Milk for 4:1 = 4 × 12 = 48 L
Milk to add = 48 − 18 = 30 L → option (c)

Why the others are wrong

(a)
51 L — 51 L of milk would make 18 + 51 = 69 L against 12 L of water, a ratio of 23:4, not 4:1.
(b)
60 L — 60 L is the size of the new mixture (48 L milk + 12 L water), not the milk added. Adding 60 L gives 78:12 = 13:2.
(d)
40 L — 40 L of milk would make 58 L against 12 L of water, 29:6, about 4.8:1, more milk than 4:1 allows.

Concept

When one liquid is added to a mixture, the other liquid does not change. Anchor the new ratio on it.

Water stays at 12 L. In 4:1, milk = 4 × water, so milk must reach 48 L; it already has 18 L.

Check: 48 : 12 = 4 : 1, and the new mixture holds 60 L.

Key facts

Adding one component leaves the other unchanged: water stays at 12 L.
Milk in the original 30 L = 3⁄5 × 30 = 18 L.
The final mixture is 48 L milk + 12 L water = 60 L.

Study next

Adding water instead of milk to reach a target ratioReplacement problems: removing some mixture and topping up with one liquidAlligation for mixing two solutions

Common traps

Choosing 60 L, the final volume, instead of the 30 L actually added.
Resetting the 30 L itself to 4:1 (24 L milk, 6 L water), which would mean removing water, not adding milk.

The same 30 L mixture at 3:2 appears at 18 Sep 2025, 12:30, Reasoning Q.19, where water is added to reach 1:1. Milk stays at 18 L there, so 6 L of water is keyed.

Related PYQs

No directly related past PYQ was found.