Selina Class 9 ICSE Solutions Mathematics : Chapter 21- Solids [Surface Area and Volume of 3-D Solids]

Class 9: Maths Chapter 21 solutions. Complete Class 9 Maths Chapter 21 Notes.

Selina Class 9 ICSE Solutions Mathematics : Chapter 21- Solids [Surface Area and Volume of 3-D Solids]

Selina 9th Maths Chapter 21, Class 9 Maths Chapter 21 solutions

Exercise 21(A)

Solution 1:

Therefore, the length, breadth and height of rectangular solid are

Solution 2:

Solution 3:

Solution 4:

Solution 5:

Solution 6:

Solution 7:

Solution 8:

Solution 9:
The area of the playground is 3650 m² and the gravels are 1.2 cm deep. Therefore the total volume to be covered will be:
3650 x 0.012 =43.8 m³.
Since the cost of per cubic meter is Rs. 6.40, therefore the total cost will be:
43.8 x Rs.6.40 = Rs.280.32

Solution 10:

Solution 11:

Solution 12:

Solution 13:
Let exterior height is h cm. Then interior dimensions are 78-3=75, 19-3=16 and h-3 (subtract two thicknesses of wood). Interior volume = 75 x 16 x (h-3) which must = 15 cu dm

Solution 14:

Solution 15:

Solution 16:

Exercise 21(B)

Solution 1:
The given figure can be divided into two cuboids of dimensions 6 cm, 4 cm, 3 cm, and 9 cm respectively. Hence, volume of solid

Solution 2:

Solution 3:
The cross section of a tunnel is of the trapezium shaped ABCD in which AB = 7m, CD = 5m and AM = BN. The height is 2.4 m and its length is 40m.

Solution 4:

Solution 5:

Solution 6:

Solution 7:

Solution 8:

Solution 9:

Solution 10:

Exercise 21(C)

Solution 1:

Solution 2:

Solution 3:

Solution 4:

Solution 5:

Solution 6:

Solution 7:

Solution 8:

Solution 9:

Solution 10:

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Selina Class 9 ICSE Solutions Mathematics : Chapter 21- Solids [Surface Area and Volume of 3-D Solids]

Download PDF: Selina Class 9 ICSE Solutions Mathematics : Chapter 21- Solids [Surface Area and Volume of 3-D Solids] PDF

Chapterwise Selina Publishers ICSE Solutions for Class 9 Mathematics :

• Chapter 1 - Rational and Irrational Numbers
• Chapter 2- Compound Interest (Without using formula)
• Chapter 3 - Compound Interest (Using Formula)
• Chapter 4- Expansions (Including Substitution)
• Chapter 5- Factorisation
• Chapter 6 - Simultaneous (Linear) Equations (Including Problems)
• Chapter 7- Indices (Exponents)
• Chapter 8- Logarithms
• Chapter 9- Triangles [Congruency in Triangles]
• Chapter 10- Isosceles Triangles
• Chapter 11- Inequalities
• Chapter 12- Mid-point and Its Converse [ Including Intercept Theorem]
• Chapter 13- Pythagoras Theorem [Proof and Simple Applications with Converse]
• Chapter 14- Rectilinear Figures [Quadrilaterals: Parallelogram, Rectangle, Rhombus, Square and Trapezium]
• Chapter 15- Construction of Polygons
• Chapter 16- Area Theorems [Proof and Use]
• Chapter 17- Circle
• Chapter 18- Statistics
• Chapter 19- Mean and Median
• Chapter 20 - Area and Perimeter of Plane Figures
• Chapter 21- Solids [Surface Area and Volume of 3-D Solids]
• Chapter 22- Trigonometrical Ratios
• Chapter 23- Trigonometrical Ratios of Standard Angles
• Chapter 24- Solution of Right Triangles
• Chapter 25- Complementary Angles
• Chapter 26- Co-ordinate Geometry
• Chapter 27- Graphical Solution (Solution of Simultaneous Linear Equations, Graphically)
• Chapter 28- Distance Formula

About Selina Publishers ICSE

Selina Publishers has been serving the students since 1976 and is one of the quality ICSE school textbooks publication houses. Mathematics and Science books for classes 6-10 form the core of our business, apart from certain English and Hindi literature as well as a few primary books. All these books are based upon the syllabus published by the Council for the I.C.S.E. Examinations, New Delhi. The textbooks are composed by a panel of subject experts and vetted by teachers practising in ICSE schools all over the country. Continuous efforts are made in complying with the standards and ensuring lucidity and clarity in content, which makes them stand tall in the industry.