A 21% reduction in wheat price lets a buyer purchase 10.5 kg more for ₹100. What is the reduced price per kg?

Introduction / Context:
Price–quantity inverse problems are common in percentage aptitude. When price falls, the same money buys more quantity. Here, a reduction of 21% increases the quantity purchasable with ₹100 by 10.5 kg. We must find the new (reduced) price per kg.

Given Data / Assumptions:

• Original price = p (₹/kg).
• Reduced price = 0.79p (21% reduction).
• Budget = ₹100. Quantity increase = 10.5 kg.

Concept / Approach:
Original quantity = 100 / p. New quantity = 100 / (0.79p). The difference equals 10.5. Set up and solve for p, then compute reduced price 0.79p. Algebra is straightforward but handle decimals carefully.

Step-by-Step Solution:

Verification / Alternative check:
At ₹2/kg reduced price, ₹100 buys 50 kg. Original price ≈ ₹2.53/kg ⇒ original quantity ≈ 39.5 kg. Difference ≈ 10.5 kg, consistent.

Why Other Options Are Wrong:
₹2.25 and ₹2.50 are near but not exact. ₹30 is irrelevant. ₹1.90 undercuts the implied figures from the difference.

Common Pitfalls:
Sign errors when forming the difference, or treating 21% of ₹100 instead of 21% of price. Always apply the reduction to price, not to the budget.

Final Answer:
Rs. 2