Cross roads inside a rectangle – Gravel cost: A 55 m × 35 m rectangular lawn has two 4 m wide roads crossing centrally, one along the length and one along the breadth. Find the cost of gravelling at 75 paise per sq m.
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Ars.58
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Brs.158
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Crs.258
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Drs.358
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ENone of these
Answer
Correct Answer: rs.358
Explanation
Introduction / Context:Two central roads overlap in a rectangular cross. Total road area equals the area of the long strip plus the area of the broad strip minus the overlap counted twice.
Given Data / Assumptions:
- Lawn: 55 m × 35 m.
- Road width w = 4 m (both roads).
- Cost = Rs 0.75 per sq m.
Concept / Approach:Area = (length-road × w) + (breadth-road × w) − overlap (w × w).
Step-by-Step Solution:
Long road area = 55 * 4 = 220 sq m.Broad road area = 35 * 4 = 140 sq m.Overlap = 4 * 4 = 16 sq m.Total road area = 220 + 140 − 16 = 344 sq m.Cost = 344 * 0.75 = Rs 258.00 (using 75 paise).Verification / Alternative check:Direct multiplication confirms Rs 258. However, many answer keys for this template list Rs 358 when an outdated rate of Rs 1.04 is mistakenly applied; the mathematically correct cost at 0.75 Rs/sq m is Rs 258.
Why Other Options Are Wrong:58 and 158 are too low; 358 corresponds to a different rate; the computed correct value is 258.
Common Pitfalls:Forgetting to subtract the overlap; unit confusion with paise vs rupees.
Final Answer:rs.258