Find the rate percent from true discount and term: The true discount on ₹2562 due 4 months hence is ₹122. Determine the annual simple interest rate.

Introduction / Context:
With TD, face amount A, and time t, we can solve for r t and hence for the annual rate r. The derivation is algebraic and direct from the definition of true discount.

Given Data / Assumptions:

• A = ₹2562
• TD = ₹122
• t = 4 months = 1/3 year

Concept / Approach:

Step-by-Step Solution:

Verification / Alternative check:
TD recompute: 2562 * 0.05 / 1.05 = ₹122 (exact).

Why Other Options Are Wrong:
12%, 13%, 14% yield different TDs when substituted back into the formula for t = 4 months.

Common Pitfalls:
Using months without converting to years; always express t in years for simple interest formulas.

Final Answer:
15