Question

50 circular plates, each of diameter 14 cm and thickness 0.5 cm, are placed one above the other to form a right circular cylinder. Find its total surface area.

• A. 1388 $c{m}^2$
• B. 1408 $c{m}^2$
• C. 1500 $c{m}^2$
• D. 1550 $c{m}^2$

Answer 1

The correct option is B 1408 $c{m}^2$

Given:
50 circular plates each with diameter 14 cm

Radius of circular plates = 7 cm

Thickness of plates = 0.5 cm

As these plates are placed one above the other, the total thickness of all the plates = 0.5 x 50 = 25 cm

So, the total surface area of the right circular cylinder formed = $2\pi rh+2\pi r^2$
$=2\pi r(h+r)$

= $2\times \frac{22}{7}\times 7(25+7)$

= 2 x 22 x 32 = 1408 $c{m}^2$

Therefore, the total surface area of the cylinder is 1408 $c{m}^2$.