Question

A closed cylindrical tank of height 280 cm and base radius 70 cm is to be made from a metal sheet. The required sheet for the same, in m², is:

• A. 15.4
• B. 14.4
• C. 13.8
• D. 12.8

Answer 1

Answer:

A. 15.4

A closed cylinder includes:

• Curved surface area

• Top + Bottom (2 circular bases)

  Convert units

Height $(h = 280 \text{ cm} = 2.8 \text{ m})$
Radius $(r = 70 \text{ cm} = 0.7 \text{ m})$

Total surface area formula

$\text{TSA} = 2\pi r h + 2\pi r^2 = 2\pi r(h + r)$

Substitute values

$= 2 \times \frac{22}{7} \times 0.7 \times (2.8 + 0.7)$
$= 2 \times \frac{22}{7} \times 0.7 \times 3.5$

Simplify

$2 \times \frac{22}{7} \times 0.7 = 4.4$

$\text{Area} = 4.4 \times 3.5 = 15.4$

Final Answer:

15.4 m²