Solution of Chapter 12. Surface Areas and Volumes (NCERT - Mathematics Exemplar Book)

A cylindrical pencil sharpened at one edge is the combination of

A surahi is the combination of

A plumbline (sahul) is the combination of (see figure)

The shape of a glass (tumbler) (see figure) is usually in the form of

The shape of a gilli, in the gilli-danda game (see figure) is a combination of

A shuttle cock used for playing badminton has the shape of the combination of

A cone is cut through a plane parallel to its base and then the cone that is formed on one side of that plane is removed. The new part that is left over on the other side of the plane is called

If a hollow cube of internal edge 22 cm is filled with spherical marbles of diameter 0.5 cm and it is assumed that space of the cube remains unfilled. Then, the number of marbles that the cube can accommodate is

A metallic spherical shell of internal and external diameters 4 cm and 8 cm, respectively is melted and recast into the form a cone of base diameter 8 cm. The height of the cone is

If a solid piece of iron in the form of a cuboid of dimensions is moulded to form a solid sphere. Then, radius of the sphere is

A mason constructs a wall of dimensions with the bricks each of size and it is assumed that space is covered by the mortar. Then, the number of bricks used to construct the wall is

Twelve solid spheres of the same size are made by melting a solid metallic cylinder of base diameter 2 cm and height 16 cm. The diameter of each sphere is

The radii of the top and bottom of a bucket of slant height 45 cm are 28 cm and 7 cm, respectively. The curved surface area of the bucket is

A medicine-capsule is in the shape of a cylinder of diameter 0.5 cm with two hemispheres stuck to each of its ends. The length of entire capsule is 2 cm. The capacity of the capsule is

If two solid hemispheres of same base radius are joined together along their bases, then curved surface area of this new solid is

A right circular cylinder of radius cm and height cm (where, h>2r) just encloses a sphere of diameter

During conversion of a solid from one shape to another, the volume of the new shape will

The diameters of the two circular ends of the bucket are 44 cm and 24 cm. The height of the bucket is 35 cm. The capacity of the bucket is

In a right circular cone, the cross-section made by a plane parallel to the base is a

If volumes of two spheres are in the ratio 64:27, then the ratio of their surface areas is

Two identical solid hemispheres of equal base radius cm are stuck together along their bases. The total surface area of the combination is 6πr².

A solid cylinder of radius and height is placed over other cylinder of same height and radius. The total surface area of the shape so formed is 4π rh+ 4πr² .

A solid cone of radius and height is placed over a solid cylinder having same base radius and height as that of a cone. The total surface area of the combined solid is

A solid ball is exactly fitted the cubical box of side a. The volume of the ball is

The volume of the frustum of a cone is where h is vertical height of the frustum and are the radii of the ends.

The capacity of a cylindrical vessel with a hemispherical portion raised upward at the bottom as shown in the figure is

The curved surface area of a frustum of a cone is where and r₂ are the radii of the two ends of the frustum and is the vertical height.

An open metallic bucket is in the shape of a frustum of a cone, mounted on a hollow cylindrical base made of the same metallic sheet. The surface area of the metallic sheet used is equal to curved surface area of frustum of a cone + area of circular base + curved surface area of cylinder.

Three metallic solid cubes whose edges are 3 cm, 4 cm and 5 cm are melted and formed into a single cube. Find the edge of the cube so formed.

How many shots each having diameter Medium 3 cm can be made from a cuboidal lead solid of dimensions

A bucket is in the form of a frustum of a cone and holds 28.490 L of water. The radii of the top and bottom are 28 cm and
21 cm, respectively. Find the height of the bucket.

A cone of radius 8 cm and height 12 cm is divided into two parts by a plane through the mid-point of its axis parallel to its base. Find the ratio of the volumes of two parts.

Two identical cubes each of volume are joined together end to end. What is the surface area of the resulting cuboid?

From a solid cube of side 7 cm, a conical cavity of height 7 cm and radius 3 cm is hollowed out. Find the volume of the remaining solid.

Two cones with same base radius 8 cm and height 15 cm are joined together along their bases. Find the surface area of the shape so formed.

Two solid cones A and B are placed in a cylindrical tube as shown in the figure. The ratio of their capacities is 2 : 1. Find the heights and capacities of cones. Also, find the volume of the remaining portion of the cylinder.

An ice-cream cone full of ice-cream having radius 5 cm and height 10 cm as shown in figure

Calculate the volume of ice-cream, provided that its part is left unfilled with ice-cream.

Marbles of diameter 1.4 cm are dropped into a cylindrical beaker of diameter 7 cm containing some water. Find the number of marbles that should be dropped into the beaker, so that the water level rises by 5.6 cm.

How many spherical lead shots each of diameter 4.2 cm can be obtained from a solid rectangular lead piece with dimensions 66 cm, 42 cm and 21 cm?

How many spherical lead shots of diameter 4 cm can be made out of a solid cube of lead whose edge measures 44 cm.

A wall 24 m long, 0.4 m thick and 6 m high is constructed with the bricks each of dimensions If the mortar occupies of the volume of the wall, then find the number of bricks used in constructing the wall.

Find the number of metallic circular disc with 1.5 cm base diameter and of height 0.2 cm to be melted to form a right circular of height 10 cm and diameter 4.5 cm.

A solid metallic hemisphere of radius 8 cm is melted and re-casted into a right circular cone of base radius 6 cm. Determine the height of the cone.

A rectangular water tank of base contains water upto a height of 5 m. If the water in the tank is transferred to a cylindrical tank of radius 3.5 m, find the height of the water level in the tank.

How many cubic centimetres of iron is required to construct an open box whose external dimensions are 36 cm, 25 cm and 16.5 cm provided the thickness of the iron is 1.5 cm. If one cubic centimeter of iron weights 7.5 g, then find the weight of the box.

The barrel of a fountain pen, cylindrical in shape, is 7 cm long and 5 mm in diameter. A full barrel of ink in the pin is used up on writing 3300 words on an average. How many words can be written in a bottle of ink containing one-fifth of a Litre?

Water flows at the rate of 10m min^-1 through a cylindrical pipe 5 mm in diameter. How long would it take to fill a conical vessel whose diameter at the base is 40 cm and depth 24 cm?

A heap of rice is in the form of a cone of diameter 9 cm and height 3.5 m. Find the volume of the rice. How much canvas cloth is required to just cover heap?

A factory manufactures 120000 pencils daily. The pencils are cylindrical in shape each of length 25 cm and circumference of base as 1.5 cm. Determine the cost of colouring the curved surfaces of the pencils manufactured in one day at Rs. 0.05 per dm².

Water is flowing at the rate of 15 kmh^-1 through a pipe of diameter 14 cm into a cuboidal pond which is 50 m long and 44 m wide. In what time will the level of water in pond rise by 21 cm?

A solid iron cuboidal block of dimensions is recast into a hollow cylindrical pipe of internal radius 30 cm and thickness 5 cm. Find the length of the pipe.

500 persons are taking a dip into a cuboidal pond which is 80 m long and 50 m broad. What is the rise of water level in the pond, if the average displacement of the water by a person is 0.04m³ ?

16 glass spheres each of radius 2 cm are packed into a cuboidal box of internal dimensions and then the box is filled with water. Find the volume of water filled in the box.

A milk container of height 16 cm is made of metal sheet in the form of a frustum of a cone with radii of its lower and upper ends as 8 cm and 20 cm, respectively. Find the cost of milk at the rate of ` 22 per L which the container can hold.

A cylindrical bucket of height 32 cm and base radius 18 cm is filled with sand. This bucket is emptied on the ground and a conical heap of sand is formed. If the height of the conical heap is 24 cm, find the radius and slant height of the heap.

A rocket is in the form of a right circular cylinder closed at the lower end and surmounted by a cone with the same radius as that of the cylinder. The diameter and height of the cylinder are 6 cm and 12 cm, respectively. If the slant height of the conical portion is 5 cm, then find the total surface area and volume of the rocket.

A building is in the form of a cylinder surmounted by a hemispherical vaulted dome and contains of air. If the internal diameter of dome is equal to its total height above the floor, find the height of the building?

A hemispherical bowl of internal radius
9 cm is full of liquid. The liquid is to be filled into cylindrical shaped bottles each of radius 1.5 cm and height 4 cm. How many bottles are needed to empty the bowl?

A solid right circular cone of height 120 cm and radius 60 cm is placed in a right circular cylinder full of water of height
180 cm. Such that it touches the bottom. Find the volume of water left in the cylinder, if the radius of the cylinder is equal to the radius to the cone.

Water flows through a cylindrical pipe, whose inner radius is 1 cm, at the rate of in an empty cylindrical tank, the radius of whose base is 40 cm. What is the rise of water level in tank in half an hour?

The rain water from a roof of dimensions drains into a cylindrical vessel having diameter of base 2 m and height 3.5 m. If the rain water collected from the roof just fill the cylindrical vessel, then find the rainfall (in cm).

A pen stand made of wood is in the shape of a cuboid with four conical depression and a cubical depression to hold the pens and pins, respectively. The dimensions of cuboid are 10 cm, 5 cm and 4 cm. The radius of each of the conical depressions is 0.5 cm and the depth is 2.1 cm. The edge of the cubical depression is 3 cm. Find the volume of the wood in the entire stand.