Question

A cylindrical vessel, open at the top, has a radius 10 cm and height 14 cm. Find
the total surface area of the vessel. (Take r = 3.14).
The length of a roller is 40 cm and its diameter is 21 cm. It takes 300 complete
revolutions to move once over to level the floor of a room. Find the area of the
room in m.
A closed metallic cylinder has its base diameter 56 cm and it is 2.25 m high. Find
the cost of the metal used to make it if it costs 80 per square metre.​

Answer 1

$1. \: r = 10cm \\ h = 14cm \\ total \: surface \: area \: of \: cylinder =2 \pi \: {r}(r + h) \\ = 2 \times \frac{22}{7} \times 10 \times 10 + 14 \\ = 44 \times 102 \\ = 4488cm^2$