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    Question

    The perimeter of a square field is 10 cm more than the

    perimeter of a rectangle. The length of the rectangle is 60 cm which is 80% of its width. If a street of width 10 cm surrounds from outside the square, then find the total cost of constructing the street at the rate of Rs. 20 per sq. cm.
    A 42000 Correct Answer Incorrect Answer
    B 64000 Correct Answer Incorrect Answer
    C 36000 Correct Answer Incorrect Answer
    D 56000 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the width of the rectangle = x cm Then, 80% of x = 60 x = 60 × 100/80 = 75 cm Perimeter of the rectangle = 2 (length + width) = 2 × (60 + 75) = 270 cm Perimeter of the square = (270 + 10) = 280 cm The sides of the square = 280/4 = 70 cm The area of the square field without street = (70)2 sq. cm = 4900 sq. cm   The area of the square field with street = (70 + 20)2 sq. cm = 8100 sq. cm The area of the street = 8100 – 4900 = 3200 sq. cm The total cost of constructing the street = 3200 × 20 = Rs. 64000

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