A decorative candle consists of two parts: a cylindrical base and a conical top. The radius of both parts is 3.5 cm. The cylindrical part is 11 cm high, while the conical part rises to a height of 9 cm above it. Determine the estimated total surface area of the candle.
Show answer & explanation
Correct answer: A
Explanation
Slant height of the cone, l = √(3.5² + 9²)
= √(12.25 + 81)
= √93.25 ≈ 9.66 cm
Total surface area of the candle = Curved surface area of the cylinder + Curved surface area of the cone + Base area of the cylinder
= 2πrh + πrl + πr²
= 2 × 22/7 × 3.5 × 11 + 22/7 × 3.5 × 9.66 + 22/7 × 3.5 × 3.5
= 242 + 106.26 + 38.5= 387 cm²