Salaries of A and B are in the ratio 3:4 and their expenditures are in the ratio 4:5. What is the ratio of their savings? I. B's saving is 25% of his salary. II. B's salary is ₹2500.

Introduction / Context:
We are given salary and expenditure ratios for A and B and must determine the ratio of their savings. Data Sufficiency asks which statements pin this down uniquely.

Given Data / Assumptions:

• Salary(A):Salary(B) = 3:4.
• Expenditure(A):Expenditure(B) = 4:5.
• Statement I: B saves 25% of his salary.
• Statement II: B's salary is ₹2500.

Concept / Approach:
Let Salary(A)=3t and Salary(B)=4t. Savings = Salary − Expenditure. With a saving percentage for B (Statement I), we can find absolute proportions for expenditures and thus A's saving, giving a unique savings ratio.

Step-by-Step Solution:
From I: B's saving = 25% of 4t = t ⇒ B's expenditure = 4t − t = 3t.Expenditure ratio A:B = 4:5 ⇒ Expenditure(A) = (4/5) * 3t = 12t/5.Savings(A) = 3t − 12t/5 = 3t/5.Thus Savings(A):Savings(B) = (3t/5):t = 3:5. Unique ratio obtained ⇒ I alone sufficient.From II alone (B salary ₹2500), without any saving percentage or additional relation, A's saving cannot be deduced ⇒ II alone not sufficient.

Verification / Alternative check:
Actual currency cancels in ratios; therefore numeric salary alone does not help.

Why Other Options Are Wrong:
II alone lacks saving information; combining is unnecessary since I already suffices.

Common Pitfalls:
Using rupee values to force a ratio; remember ratios are scale-free unless a second numerical constraint is provided.

Final Answer:
Statement I alone suffices; savings ratio is 3:5.