Difficulty: Easy
Correct Answer: 60
Explanation:
Introduction / Context:Translate total fence cost to total perimeter, then use the linear relation between length and breadth to solve the dimensions.
Given Data / Assumptions:
Concept / Approach:P = 2(L + B). Substitute L = B + 20 and solve for B, then get L.
Step-by-Step Solution:
1) L + B = 200/2 = 100.2) (B + 20) + B = 100 ⇒ 2B = 80 ⇒ B = 40.3) L = 40 + 20 = 60 m.Verification / Alternative check:Perimeter check: 2(60 + 40) = 200 m; multiplied by 26.5 ⇒ Rs 5300.
Why Other Options Are Wrong:40 and 50 are not the length; 120 is the sum of sides? Incorrect. “None of these” is not needed since the exact length is 60.
Common Pitfalls:Forgetting to halve the perimeter when solving L + B; mixing up which side is longer.
Final Answer:60.
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