NCERT Solutions for Class 9 Maths Chapter 13

Important NCERT Questions

Surface Areas and Volumes

NCERT Books for Session 2022-2023

CBSE Board, UP Board and Other state Boards

EXERCISE 13.1

Page No:213

Questions No:2

# The length, breadth and height of a room are 5 m, 4 m and 3 m respectively. Find the cost of white washing the walls of the room and the ceiling at the rate of Rs 7.50 per m².

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Lenght of room l = 5 m, breadth b = 4 m and height h = 3 m

Area of four walls and ceilling = Total surface area of room – area of floor

= 2(lb + bh + hl) – lb

= 2(5 × 4 + 4 × 3 + 3 × 5) – 5 × 4 m²

= 2(20 + 12 + 15) – 20 m²

= 2(47) – 20 m²

= 94 – 20 = 74 m²

Therefore, the area of four walls and ceilling = 74 m²

Hence, the cost of white washing the walls of walls of the room and the ceilling

= Rs 7.50 × 74 = Rs. 555.00