Multiple choice

From a solid cylinder of height 4 cm and radius 3 cm, a conical cavity of height 4 cm and of base radius 3 cm is hollowed out. What is the total surface area of the remaining solid?

  1. $45\pi cm^2$
  2. $55\pi cm^2$
  3. $48\pi cm^2$
  4. $50\pi cm^2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The remaining solid has a cylindrical outer surface (2πrh = 24π cm²) plus a circular top (πr² = 9π cm²). The inner conical cavity has lateral surface area πrl = π × 3 × 5 = 15π cm². Total = 24π + 9π + 15π = 48π cm². Option A (45π) incorrectly omits the top surface. Option B (55π) and D (50π) are miscalculations.

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