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WAEC 2022 · Paper 1 · Q24

A cylinder, open at one end, has a radius of 3.5 cm3.5\text{ cm} and height 8 cm8\text{ cm}. Calculate the total surface area. [Take π=227]\left[\text{Take }\pi = \frac{22}{7}\right]

Worked solution (try it first)
  1. Open at one end: the curved surface plus one circle.
  2. Curved surface: 2πrh=2×227×3.5×82\pi rh = 2 \times \frac{22}{7} \times 3.5 \times 8
    =176 cm2= 176\text{ cm}^2.
  3. One end: 227×3.52=38.5 cm2\frac{22}{7} \times 3.5^2 = 38.5\text{ cm}^2.
  4. Total: 176+38.5=214.5 cm2176 + 38.5 = 214.5\text{ cm}^2, option D.

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