ICSE Books Solutions

Selina Concise Mathematicsclass 6 ICSE Solutions – Mean and Median Selina Concise Mathematicsclass 6 ICSE Solutions – Mean and Median EXERCISE 34 (A) Question 1. Find the mean of : (i) 7,10, 4 and 17 (ii) 12, 9, 6,11 and 17 (iii) 3, 1, 5, 4, 4 and 7 (iv) 7, 5, 0, 3, 0, 6, 0, 9, 1 and 4 (v) 2.1, 4.5, 5.2, 7.1 and 9.3 (vi) 5, 2.4, 6.2, 8.9, 4.1 and 3.4 Answer: Question 2. Find the mean of : (i) first eight natural numbers (ii) first six even natural numbers (iii) first five odd natural numbers (iv) all prime numbers upto 30 (v) all prime numbers between 20 and 40. Answer: (i) The first eight natural numbers are 1, 2, 3, 4, 5, 6, 7, 8 ∴Sum of these observations =1+2+3+4+5+6+7+8=36 and, number of their observations = 8 ∴Required mean =   = 4.5 (ii) The first six even natural numbers are 1 = 2, 4, 6, 8, 10, 12 ∴Sum of these observations = 2, 4, 6, 8, 10, 12 = 42 and, number of their observations = 6 ∴ Required mean =   = 7 (iii) The first five odd natural numbers are = 1,...

Selina Concise Mathematics Class 6 ICSE Solutions – Perimeter and Area of Plane Figures Selina Concise Mathematics Class 6 ICSE Solutions – Perimeter and Area of Plane Figures IMPORTANT POINTS 1. Perimeter: It is the length of the boundry of the given figure. (i) Perimeter of a triangle = Sum of its three sides. (ii) Perimeter of rectangle = 2 (length + breadth) (iii) Perimeter of square = 4 x side. 2. Area: Area is the measure of surface of the plane covered by a closed plane figure. In other words, we can say that area of a closed plane figure is the measure of its interior region. (i) Area of rectangle = length x breadth (ii) Area of square = (side)². 3. Units of measurement of perimeter and area : (i) Perimeter is measured in centimetre (cm) metre (m) or millimetre (mm). (ii) Area is measured in square mm, square cm or square metre. EXERCISE 32 (A) Question 1. What do you understand by a plane closed figure? Solution: Any geometrical plane figure bounded by lines (straight or cur...

Selina Concise Mathematics Class 6 ICSE Solutions -Recognition of Solids Selina Concise Mathematics Class 6 ICSE Solutions -Recognition of Solids EXERCISE 31 Question 1. Identify the nets which can be used to form cubes :   Solution: Nets for a cube are (ii), (iii) and (iv). Question 2. Draw at least three different nets for making cube. Solution:   Question 3. The dimensions of a cuboid are 6 cm, 4 cm and 3 cm. Draw two different types of oblique sketches for this cuboid. Solution:   Question 4. Two cubes, each with 3 cm edge, are placed side by side to form a cuboid. For this cuboid, draw : (i) an oblique sketch (ii) an isometric sketch. Solution:     Question 5. The figure, given below, shows shadows of some 3D objects, when seen under the lamp of an overhead projector :    In each case, name the object. Solution:   Question 6. Look at the solids, drawn below, and fill the given chart.     Solution:   P. Q. Using Euler’s formula,...

Selina Concise Mathematics Class 6 ICSE Solutions – Revision Exercise Symmetry (Including Constructions on Symmetry) Selina Concise Mathematics Class 6 ICSE Solutions – Revision Exercise Symmetry (Including Constructions on Symmetry) IMPORTANT POINTS 1. Concept of Symmetry (Linear Symmetry) : Consider a plane mirror mm’. If your face F is at a distance ‘d’ before the mirror ; the image F, of your face is also formed behind the mirror at distance “d” from it. Now, if the Figure 1, given alongside, is folded about the mirror mm’, the object F and its image F’ coincide. Since on folding the figure about mm’ its two parts exactly coincide, we say that the figure is symmetrical about the mirror line mm’. For the reason, the mirror line mm’ is called line of symmetry of the whole figure including face F, its image F’ and the mirror mm’. Keep in Mind : in order to check, whether a given figure is symmetrical about a line in it or not; fold the figure about that line. If part of the figure, wh...

Selina Concise Mathematics Class 6 ICSE Solutions – The Circle Selina Concise Mathematics Class 6 ICSE Solutions – The Circle IMPORTANT POINTS 1. A circle is a round enclosed figure, whose mid-point is called its centre. 2. The line segment joining the centre to any point on the circle is called a radius. A centre has infinite radii and all radii of a circle are equal. 3. A line segment which contains the centre of the circle and whose ends points lie on the circle is called diameter of the circle. Diameters of a circle are also equal. 4. Parts of a circle: A circle has three parts (i) Interior (ii) Exterior and (iii) Circle itself. 5. Concentric circles: Two or more circles having the same centre but different radii are called concentric circles. 6. Chord of a circle: A line which divides the circle into two parts is called chord of the circle. Diameter is the longest chord of the circle. 7. Segment of a circle: When a chord divides the circle into two unequal parts, the bigger p...

Selina Concise Mathematics Class 6 ICSE Solutions – Polygons Selina Concise Mathematics Class 6 ICSE Solutions – Polygons IMPORTANT POINTS 1. Polygon : A closed plane geometrical figure, bounded by atleast three line segments, is called a polygon. The adjoining figure is a polygon as it is : (i) Closed (ii) bounded by five line segments AB, BC, CD, DE and AE. Also, it is clear from the given polygon that: (i) the line segments AB, BC, CD, DE and AE intersect at their end points. (ii) two line segments, with a common vertex, are not collinear i.e. the angle at any vertex is not 180°. A polygon is named according to the number of sides (line-segments) in it: Note : No. of sides : 3 4 5 6 Name of polygon : Triangle Quadrilateral Pentagon Hexagon 2. Sum of Interior Angles of a Polygon 1. Triangle : Students already know that the sum of interior angles of a triangle is always 180°. i.e. for ∆ ABC, ∠B AC + ∠ABC + ∠ACB = 180° ⇒ ZA + ZB + ZC = 180° 2. Quadrilateral : Consider a quadr...

Selina Concise Mathematics Class 6 ICSE Solutions – Quadrilateral Selina Concise Mathematics Class 6 ICSE Solutions – Quadrilateral IMPORTANT POINTS 4. Quadrilateral: A quadrilateral is a plane figure enclosed by four sides. It has four sides, four interior angles and four vertices. In quadrilateral ABCD, shown alongside: (i) four sides are : AB, BC, CD and DA. (ii) four angles are : ∠ABC,∠BCD, ∠CDA and ∠DAB ; which are numbered∠1, ∠2, ∠3 and ∠4 respectively. (iii) four vertices are : A, B, C and D. 5. Diagonals of a Quadrilateral : The line segments joining the opposite vertices of a quadrilateral are called its diagonals. The given figure shows a quadrilateral PQRS with diagonals PR and QS. 6. Types of Quadrilaterals : 1. Trapezium: A trapezium is a quadrilateral in which one pair of opposite sides are parallel. The figure, given alongside, shows a trapezium as its sides AB and DC are parallel i.e. AB || DC. When the non-parallel sides of the trapezium are equal in length, it is c...