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NECO 2024 · Paper 1 · Q44

Calculate the surface area of a sphere with diameter 10.4 cm10.4\text{ cm}, correct to 3 significant figures. [Take π=3.142\pi = 3.142]

Worked solution (try it first)
  1. Radius =10.4÷2=5.2= 10.4 \div 2 = 5.2 cm.
  2. The surface area of a sphere is 4πr24\pi r^2.
  3. 4×3.142×5.22=4×3.142×27.044 \times 3.142 \times 5.2^2 = 4 \times 3.142 \times 27.04
    =339.84= 339.84.
  4. To 3 significant figures that is 340 cm2340\text{ cm}^2, option C.

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