Unit conversion and unitary method: If the cost of 1/4 kg of a commodity is Rs 0.60, what is the cost of 200 g of the same commodity?

Introduction / Context:
This is a classic unitary-method and unit-conversion question. We convert kilograms to grams, find a per-gram cost (or scale directly), and then compute the cost for the requested weight. Getting the conversion right avoids the most common mistakes.

Given Data / Assumptions:

• 1/4 kg costs Rs 0.60
• We need the cost of 200 g
• 1 kg = 1000 g

Concept / Approach:
First, compute the cost per kilogram from the given quarter kilogram price. Then multiply by the fraction of a kilogram represented by 200 g (which is 0.2 kg). Alternatively, use direct proportionality from 250 g to 200 g since 1/4 kg = 250 g.

Step-by-Step Solution:

Verification / Alternative check:
Proportion from grams: 250 g costs 60 paise ⇒ 1 g costs 60/250 = 0.24 paise ⇒ 200 g costs 200 * 0.24 = 48 paise. Same result confirms correctness.

Why Other Options Are Wrong:

• 42, 40, 50, 60 paise: These arise from rounding or wrong gram-to-kilogram scaling. Only 48 paise matches exact proportionality.

Common Pitfalls:
Using 1 kg = 100 g (wrong) or converting 200 g incorrectly as 0.02 kg. Also, mixing paise and rupees (e.g., treating 0.48 as 48 rupees) leads to huge errors.

Final Answer:
48 paise