Jaspal buys a cow for Rs 3000 and sells to Dharampal the same day for Rs 3600, allowing 2 years’ credit at 10% p.a. simple interest. What is Jaspal’s gain percentage?

Introduction / Context:
When selling on credit, compare the present worth of the credit price at the going rate with the cash cost price to determine profit.

Given Data / Assumptions:

• CP = Rs 3000 (cash today).
• SP (due in 2 years) = Rs 3600.
• Rate r = 10% p.a. simple; discounting to present worth applies.

Concept / Approach:
Present worth PW of an amount A due after t years at simple interest r% is A/(1 + r t/100). Profit is PW − CP if positive; else loss.

Step-by-Step Solution:

Verification / Alternative check:
Viewed forward: If Jaspal invested Rs 3000 at 10% for 2 years, it would grow to 3600, equal to the credit selling price; hence zero advantage.

Why Other Options Are Wrong:
Any nonzero percentage contradicts the exact equality of PW and CP.

Common Pitfalls:
Treating Rs 3600 as if cash today without discounting.

Final Answer:
Nil