Monthly-to-annual salary via ratio with difference: A, B, and C earn monthly salaries in the ratio 2 : 3 : 5. If C’s monthly salary exceeds A’s by Rs. 1200, what is B’s annual salary?

Introduction / Context:
Salary ratio problems with a known difference can be solved by representing each salary as a multiple of a common part. The difference maps to the difference in ratio parts times the value per part.

Given Data / Assumptions:

• Monthly ratio A : B : C = 2 : 3 : 5.
• C − A = 1200 per month.
• Need B’s annual (12 months) salary.

Concept / Approach:
Let A = 2k, B = 3k, C = 5k. Then C − A = 3k = 1200 ⇒ k = 400. Hence B’s monthly salary is 3k and annual is 12 times this amount.

Step-by-Step Solution:
3k = 1200 ⇒ k = 400.B (monthly) = 3k = 1200.B (annual) = 1200 * 12 = Rs. 14400.

Verification / Alternative check:
A = 2k = 800; C = 5k = 2000; indeed C − A = 1200, and the ratio 800 : 1200 : 2000 reduces to 2 : 3 : 5.

Why Other Options Are Wrong:

• Rs. 24000 does not follow from k = 400.
• Rs. 1200 is B’s monthly, not annual salary; Rs. 2000 is unrelated.

Common Pitfalls:

• Using annual difference 1200 * 12 incorrectly; the difference given is monthly.

Final Answer:
Rs. 14400