The maximum length of a pencil that can be kept in a rectangular box of dimensions

12 cm x 9 cm x 8 cm, is

A cylinder is open at both ends and is made of 1.5-cm-thick metal. Its external diameter is 12 cm and height is 84 cm. What is the volume of metal used in making the cylinder? Also, find the weight of the cylinder if 1 cm ' of the metal weighs 7.5 g.

Hint. External radius = 6 cm, internal radius = 4.5 cm.

Volume of metal =

.

The length of a metallic tube is 1 metre, its thickness is 1 cm and its inner diameter is 12 cm. Find the weight of the tube if the density of the metal is 7.7 grams per cubic centimetre.

Hint. Weight of 1 cm³ of metal = 7.7 g.

Its volume =

The total surface area of a cube is 150 cm². Its volume is

The volume of a cube is 343 cm³. Its total surface area is