S.chand Class 8 Maths Solution Chapter 17 Volume and Surface Area of Solids Exercise 17 A

 Exercise 17 A

Question 1

Find the surface area of each of the cuboids whose dimensions are given below:

	(i)	(ii)	(iii)	(iv)	(v)	(vi)
l	5 cm	6 cm	10 cm	4 cm	$5 \frac{1}{2}$ cm	16 cm
b	4 cm	3 m	8 cm	1.7 cm	4 cm	8 cm
h	3 cm	2 m	5 cm	2.3 cm	$10 \frac{1}{2}$ cm	6 cm

2. Find the surface area of the following cubes :

(a) $l=8 \mathrm{~cm}$

(b) $l=12 \mathrm{~cm}$

(c) $l=\frac{1}{2} \mathrm{~m}$

(d) $l=5 \mathrm{dm}$

(e) $l=1.2 \mathrm{~m}$

(f) $l=2.25 \mathrm{~m}$

3. The total surface area of a cube is $54 \mathrm{~cm}^{2}$. What is the length of its sides ?

4. Find the surface area of a wooden box which is in the shape of a cube, if the edge of the box is $27 \mathrm{~cm}$.

5. Find the cost of painting the all round outer surface of a box with lid $60 \mathrm{~cm}$ long, $40 \mathrm{~cm}$ wide and $30 \mathrm{~cm}$ high at 50 p per $20 \mathrm{~cm}^{2}$.

6. The dimensions of an oil tin are $26 \mathrm{~cm} \times 26 \mathrm{~cm} \times 45 \mathrm{~cm}$. Find the area of the tin sheet required for making 20 such tins. If $1 \mathrm{sq} \mathrm{m}$ of the tin sheet costs $₹ 10$, find the cost of tin used for these 20 tins.

7. Find the area of the thin sheeting required for making an open cistern (i.e., without a lid), $5 \mathrm{~m}$ long, $3 \mathrm{~m}$ wide, $4 \mathrm{~m}$ deep.

8. A swimming pool is $20 \mathrm{~m}$ in length, $15 \mathrm{~m}$ in breadth, and $4 \mathrm{~m}$ in depth. Find the cost of cementing its floor and walls at the rate of $₹ 12$ per square metre.

9. Two cubes, each of side $15 \mathrm{~cm}$ are joined end to end. Find the surface area of the resulting cuboid.

Multiple Choice Questions (MCQs)

10. The perimeter of one face of a cube is $20 \mathrm{~cm}$. Its total surface area is :

(a) $2400 \mathrm{~cm}^{2}$

(b) $150 \mathrm{~cm}^{2}$

(c) $120 \mathrm{~cm}^{2}$

(d) $96 \mathrm{~cm}^{2}$

11. A cube of edge $5 \mathrm{~cm}$ is cut into cubes, each of edge $1 \mathrm{~cm}$. The ratio of the total surface area of one of small cubes to that of the large cube is :

(a) $1: 125$

(b) $1: 5$

(c) $1: 625$

(d) $1: 25$

12. Find the cost of painting the four walls of a room 10 metres long, 5 metres broad and 6 metres high at the cost of $₹ 4$ per square metre.

(a) ₹ 720

(b) ₹ 880

(c)₹ 360

(d) ₹ 1200

High Order Thinking Skills (HOTS)

13. The area of the four walls in a room is $120 \mathrm{~m}^{2}$. The length of twice the breadth. If the height of the room is $4 \mathrm{~m}$, find the area of the floor.