Rectangle — Area 3584 m^2 and Sides in Ratio 7 : 2: Find the perimeter of the rectangle (in metres).

Difficulty: Medium

Correct Answer: 288 m

Explanation:


Introduction / Context:
This is a scale-factor problem: area fixes k^2 when sides are in a given ratio. After computing k, sides follow, and the perimeter is twice the sum. Carry exact integers to avoid rounding in the final perimeter value.



Given Data / Assumptions:

  • Sides = 7k and 2k (metres)
  • Area = 3584 m^2 ⇒ (7k)(2k) = 14k^2
  • Perimeter P = 2(7k + 2k)


Concept / Approach:
Solve 14k^2 = 3584 ⇒ k^2 = 256 ⇒ k = 16. Then compute sides and the perimeter. All numbers are integral, giving an exact perimeter.



Step-by-Step Solution:

k^2 = 3584 / 14 = 256 ⇒ k = 16.Sides: 7k = 112 m; 2k = 32 m.Perimeter P = 2(112 + 32) = 2 * 144 = 288 m.


Verification / Alternative check:

Area check: 112 * 32 = 3584 m^2 (matches).


Why Other Options Are Wrong:

  • 246, 286, 292 are near misses from arithmetic errors.
  • 274 is unsupported by the derived dimensions.


Common Pitfalls:

  • Treating 7 : 2 as a sum instead of a product when using area.


Final Answer:
288 m.

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