SSC CGL 2025 Tier-I · 14 September 2025, Shift 2 · General Intelligence and Reasoning · Question 19 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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A 25 L solution has sugar: water = 3:2. How much water to make sugar: water = 1:1?

(a)2.5 L
(b)5 L
(c)7.5 L
(d)10 L

Answer

Why

Correct — B. Only water is added, so the sugar stays fixed. Find it first.

Rule: when one part is added, the other part is the anchor.

Sugar: 3⁄5 × 25 = 15 L
Water: 2⁄5 × 25 = 10 L

For 1 : 1, water must equal sugar: 15 L
Water to add: 15 − 10 = 5 L, option (b).

Why the others are wrong

(a)
2.5 L — 2.5 L comes from splitting the old 25 L as 12.5 : 12.5. Adding water raises the total while the sugar stays at 15 L, so the water must reach 15 L.
(c)
7.5 L — 7.5 L overshoots: water becomes 17.5 L against 15 L of sugar, a ratio of 6 : 7.
(d)
10 L — 10 L doubles the water to 20 L. Sugar to water is then 15 : 20 = 3 : 4, not 1 : 1.

Concept

When one component is added to a mixture, the other component is the anchor: its quantity is the same before and after. Split the mixture by its ratio, hold the unchanged part fixed, and read the new amount of the added part from the target ratio.

Here 3 : 2 on 25 L gives 15 L of sugar and 10 L of water. A 1 : 1 ratio needs the water to match the 15 L of sugar.

Check: 15 L of sugar and 10 + 5 = 15 L of water give 1 : 1, and the solution grows from 25 L to 30 L.

Key facts

A total T in the ratio a : b splits as a⁄(a + b) × T and b⁄(a + b) × T.
25 L at 3 : 2 is 15 L of sugar and 10 L of water.
Adding water changes the ratio but not the amount of sugar.

Study next

Adding the second component to cut a percentage, where the water stays fixed insteadReplacement: drawing off some mixture and topping up with one componentMixing two solutions that hold different ratios

Common traps

Applying 1 : 1 to the old 25 L, 12.5 L each, when the total grows as water goes in. That gives 2.5 L.
Adding as much water as is already there, 10 L, which gives 15 : 20 = 3 : 4.

The same anchor decides 18 Sep 2025, 12:30, Reasoning Q.19: 30 L of milk and water at 3 : 2 holds 18 L of milk and 12 L of water, so 6 L of water makes it 1 : 1.

23 Sep 2024, 09:00, Quant Q.20 asks for 50% water in 32 L at 5 : 3 milk to water, which needs 8 L.

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