Charge of cellophane paper is Rs. 40 per kg. How must expenditure would be there to cover a cube of edge 25 cm with a cellophane paper, if one kg of paper covers 50 sq.cm. area?

Consider the following statements:

I. If the height of a cylinder is doubled, the area of the curved surface is doubled.

II. If the radius of a hemispherical solid is doubled, its total surface area becomes fourfold.

Which of the above statement(s) is / are true:

From a solid cylinder whose height is 2.4 cm and diameter is 1.4 cm, a conical cavity of same height and same diameter is carved out. The total surface area of the remaining solid is:

Use $\pi = \frac{22}{7}$

The solid and the Surface area (S.A) of the following solids are given below.

(A) A cube of edge 9 cm., S.A = $486 \text{ cm}^2$

(B) A cuboid of 18 cm. long, 14 cm. width and 7 cm. height, S.A = $108 \text{ cm}^2$

(C) A cylinder with diameter of 14 cm. and height 80 cm., S.A = $3520 \text{ cm}^2$

(D) A sphere with radius of 14 cm., S.A = $2004 \text{ cm}^2$

Choose the correct answer from the options given below:

If a metallic rod of 10 cm length and 2 cm radius is stretched into a wire of 40 m length having uniform thickness, then find the radius of the stretched wire.

Radius of the base and height of a cone are 5 cm and 12 cm respectively. Find its slant height.

A solid sphere of radius 15 cm is melted into a hollow cylinder of uniform thickness. If the external radius of the base of the cylinder is 9 cm and its height is 100 cm, find the uniform thickness of the cylinder.