Question

A closed metallic cylindrical box is 1.25 m high and its base radius is 35 cm. If the sheet metal costs Rs. 80 per m${}^2$, the cost of the material used in the box is

• A. Rs. 281.60
• B. Rs. 290
• C. Rs. 340.50
• D. Rs. 500

Answer 1

The correct option is A Rs. 281.60

T.S.A. of cyl $=2\pi rh+2\pi r^2=2\pi \times \left(\frac{35}{100}\right)\times 1.25+2\pi {\left(\frac{35}{100}\right)}^2$

$\Rightarrow TSA=3.52m^2$ & as cost of $1m^2$ is Rs 80

$\Rightarrow$ Total cost $=3.52\times 80=Rs281.6$