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\ 06-Jan-2025 Bharat Arora Proof-7 Reader’s Sign _______________________ Date __________

35
Radius of the semi-cylindrical roof r = m
2
Height of the cuboidal part of the stable h = 40 m

Breadth of the stable b = 35 m
Length of the stable l = 70 m
1 1
Area to be painted = one l × h + two b × h + × 2πrl + 2 × × πr²
2 2

1  22 35   1 22 35 35
= 70 × 40 + 2 × 35 × 40 + ×  2 × × × 70 + 2 ×  × × × 

2  7 2   2 7 2 2 
= 2800 + 2800 + 3850 + 962.5

= 10412.5 m²
Since, the cost of painting the exterior of stable = `2/m²

Therefore, the total cost of painting = `(10412.5 × 2) = `20,825.

Maths Talk
Discuss how the two given boxes are alike and how they are different. Also, find
which box has a larger lateral surface area.

7 cm
7 cm

7 cm
7 cm 7 cm

Practice Time 10D

1. Find the lateral and total surface area of the following solid shapes. (Keep answers in decimals
up to two places)
6 cm
(a) 4 cm (b) (c) 6 cm
12 cm
5 cm
4 cm 8 cm
4 cm
2. Two cubes, each with an edge of 10 cm are joined face to face. Find the surface area of the cuboid
thus formed.

3. Raman painted the outer surface of a cabinet that measures 10 m by 8 m by 2.5 m. Find the surface
area he covered if he painted all faces except the bottom of the cabinet.

4. The internal measures of a cuboidal hall (in the order length, breadth and height) are 18 m × 10 m
× 5 m. Find the total cost of whitewashing all the four walls of a room if the cost of whitewashing is
`50 per m . What will be the cost of whitewashing if the ceiling of the room is also whitewashed?
2

Mathematics-8 248