Unitary method: If 24 oranges cost ₹ 72, find the cost of 120 oranges (assume a constant rate).

Introduction / Context:
This is a direct proportion cost question. When unit price is constant, total cost scales linearly with quantity. We apply the unitary method to find the cost of a larger batch.

Given Data / Assumptions:

• 24 oranges cost ₹ 72.
• Find cost for 120 oranges.
• Assume uniform price per orange.

Concept / Approach:
First compute the price per orange, then multiply by 120 to obtain the total cost for that quantity.

Step-by-Step Solution:

Verification / Alternative check:
Proportion scaling: 120 is 5 times 24, so the cost is also 5 times ₹ 72, i.e., ₹ 360. This matches the unit rate calculation.

Why Other Options Are Wrong:

• ₹ 180: Equals half of ₹ 360; would correspond to 60 oranges, not 120.
• ₹ 172 and ₹ 500: Do not align with the linear scaling from the given unit cost.

Common Pitfalls:
Forgetting to scale the cost by the same factor as the quantity (here, 5×). Always confirm by comparing ratios to ensure consistency.

Final Answer: