S.chand books class 8 maths solution chapter 27 Volume and Surface Area of Solids exercise 27 B

 EXERCISE 27 B

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Q1 | Ex-27B | Class 8| S.Chand | Composite maths |Volume and Surface Area of Solids| myhelper

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Question 1

Copy and complete the given table for a cylinder (use pi=22/7)

	Radius	Height	Curved Surface Area	Area of Base	Total Surface Area
(i)	14cm	20cm
(ii)	0.28cm	45cm
(iii)	5.6cm	13.2cm

Sol :

C.SA (2πrh)

(i)=2π(14)(20)
=1760cm²

(ii)=2π(0.28)(45)
=79.2cm²

(iii)=2π(5.6)(13.2)
=464.64cm²

Area of base(πr²)
(i)=π(14)²
=616cm²

(ii)=π(0.28)²
=0.2464cm²

(iii)=π(5.6)²
=98.4707cm²

Total Surface Area(=2πr(h + r))

(i)=2π(14)[20+14]

=2992cm²
(ii)=2π(0.28)[45+0.28]

=79.6928cm²
(iii)=2π(5.6)[13.2+5.6]
=661.76cm²

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Q2 | Ex-27B | Class 8| S.Chand | Composite maths |Volume and Surface Area of Solids| myhelper

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Question 2

Find the radius of a cylinder whose height is 42cm and whose curved surface area is 8448 cm².

Sol :

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Q3 | Ex-27B | Class 8| S.Chand | Composite maths |Volume and Surface Area of Solids| myhelper

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Question 3

The total surface area of a right circular cylinder of radius 7cm is 1188cm² . Find its height

Sol :

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Q4 | Ex-27B | Class 8| S.Chand | Composite maths |Volume and Surface Area of Solids| myhelper

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Question 4

Four times the area of the curved surface of a cylinder is equal to 6 times the sum of the area of its bases if its height is 14cm , find the curved surface area .

Sol :

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Q5 | Ex-27B | Class 8| S.Chand | Composite maths |Volume and Surface Area of Solids| myhelper

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Question 5

The circumference of the base of a right circular cylinder is 176cm and it is 1m high . Find the lateral surface area of the cylinder.

Sol :

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Q6 | Ex-27B | Class 8| S.Chand | Composite maths |Volume and Surface Area of Solids| myhelper

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Question 6

A cylindrical vessel open at the top has a diameter of 21cm and height 16cm. Find the cost of tin plating it on the inside at the rate of 10 rupees per hundred square centimetres.

Sol :

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Q7 | Ex-27B | Class 8| S.Chand | Composite maths |Volume and Surface Area of Solids| myhelper

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Question 7

A hollow metal pipe is 63cm long. The inner diameter of cross-section is 4cm and the outer diameter is 4.8cm. Find the total surface area of the pipe.

Sol :