Mat for a room: A room is 15 ft by 12 ft. A mat is placed leaving a uniform 1.5 ft margin from each wall. Find the cost of the mat at Rs 3.50 per square foot.
Aptitude
Area
Difficulty: Easy
Choose an option
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A378
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B472.5
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C496
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D630
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E315
Answer
Correct Answer: 378
Explanation
Introduction / Context:This problem combines inner rectangle dimensions after margins with unit rate multiplication for cost.
Given Data / Assumptions:
- Outer room: 15 ft by 12 ft
- Uniform margin: 1.5 ft on all sides
- Rate = Rs 3.50 per sq ft
Concept / Approach:Inner mat dimensions subtract twice the margin from each side. Area = length * breadth. Cost = area * rate.
Step-by-Step Solution:
Inner length = 15 - 2*1.5 = 12 ftInner breadth = 12 - 2*1.5 = 9 ftArea = 12 * 9 = 108 sq ftCost = 108 * 3.5 = Rs 378Verification / Alternative check:3.5 * 100 = 350; 3.5 * 8 = 28; total 378. Correct.
Why Other Options Are Wrong:472.5, 496, 630, 315 do not match the exact computation 108 * 3.5.
Common Pitfalls:Subtracting margin only once, or applying it to area directly rather than dimensions first.
Final Answer:378