WAEC 2024 Mathematics · Question 42

The perimeter of a rectangular garden is 90 m. If the width is 7 m less than the length, find the length of the garden.

Options

A.19 m
B.23 m
C.24 m
D.26 m

Answer: D. 26 m

Explanation written with AI and checked against the answer key

Analyze the question: We are given the perimeter of a rectangle (90 m) and a relationship between width and length (width = length − 7). We need the length. Concept: Perimeter of a rectangle = 2(length + width) = 2(l + w) Solution: Let the length = l, so the width = l − 7. 2(l + l − 7) = 90 2(2l − 7) = 90 2l − 7 = 45 2l = 52 l = 26 m Check: Width = 26 − 7 = 19 m. Perimeter = 2(26 + 19) = 2(45) = 90 m ✓ Answer: The length is 26 m, which is option D. Note that 19 m (option A) is the width, not the length, which is a common trap. Tip: Always re-read what the question asks for (length or width) before choosing. A quick way to start is to divide the perimeter by 2 to get l + w = 45, then find two numbers that add to 45 and differ by 7: 26 and 19.

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