Question

A vessel is in the form of a hollow hemisphere mounted by a hollow cylinder. The diameter of the hemisphere is 28 cm, and the total height of the vessel is 20 cm. Find the inner surface area (in cm?) of the vessel. (Use ∏=22/7)

• A. 1720
• B. 1760
• C. 1780
• D. 1740

Answer 1

Answer:

B. 1760

Radius$(r = \frac{28}{2} = 14) cm$

Total height = 20 cm ⇒ Height of cylinder
$h = 20 - 14 = 6 \text{ cm}$

Inner surface area = Curved surface area of hemisphere + Curved surface area of cylinder

Hemisphere CSA:
$2\pi r^2 = 2 \times \frac{22}{7} \times 14^2 = 1232$

Cylinder CSA:
$2\pi r h = 2 \times \frac{22}{7} \times 14 \times 6 = 528$

Total inner surface area:
$1232 + 528 = 1760$

Answer: 1760 cm²