a room is 9m long, 8m broad and 6m high. It has two doors of size of 3m *1.5m and two windows each of size 1.5m*1m. Find the cost of white washing the walls of room at the rate of ₹5 per square meter
Answers
★ Given:
→ Room:
Length of the room = 9 m
Breadth of the room = 8 m
Height of the room = 6 m
→ 2 Doors, each of dimension:
Length = 3 m
Breadth = 1.5 m
→ 2 windows, each of dimension:
Length = 1.5 m
Breadth = 1 m
→ White-washing
Cost of white-washing 1 m² = Rs 5
★ To Find
The total cost of whitewashing.
★ Steps to Solve:
→ Find LSA of walls
→ Find Area of the doors and windows
→ Subtract the area from the LSA
→ Multiply with the cost of white washing
★ Formulae to Use:
→
→
★ Solution:
LSA of room:
Length = 9 m
Breadth = 8 m
Height = 6 m
LSA = 2 (lh + bh)
= 2 [(9x6)+(8x6)]
= 2 x [54 + 48]
= 2 x 102
= 204 m²
Area of Doors
Length = 3 m
Breadth = 1.5 m
Area of rectangle = 2 (l + b)
= 2 x (3 + 1.5)
= 2 x 4.5
= 9 m²
No. of doors = 2
Total area = 9 x 2 = 18 m²
Area of Windows:
Length = 1.5 m
Breadth = 1 m
Area of rectangle = 2 (l + b)
= 2 x (1.5 + 1)
= 2 x 2.5
= 5 m²
No. of windows = 2
Total area = 5 x 2 = 10 m²
Total area covered by the doors and windows = 18 + 10 = 28 m²
Area of wall to be whitewashed = LSA - Total area of doors and windows
= 204 - 28
= 176 m²
Cost of whitewashing 1 m² = Rs 5
Cost of whitewashing 176 m² = 176 x 5
= Rs 880
Hence the required correct answer is Rs 880.
Length of the wall = 9 m
Breadth of the wall = 8 m
Height of the wall = 6 m
Thus, Area of 4 walls = 2h(l + b)
= 2 x 6 (9 + 8)
= 12 x 17
= 204 sq. mtrs.
Length of 1 door = 3 m
Breadth of 1 door = 1.5m
Thus, Area of 2 doors = 2 (3 x 1.5)
= 2 x 4.5
= 9 sq. mtrs
Length of 1 window = 1.5 m
Breadth of 1 window = 1 m
Area of 4 walls = 4( 1.5 x 1 ) m^2
= 6 m^2
Area of wall that is to be whitewashed = (204 - 9 - 6) sq.
mtrs.
= 189 m^2
Cost of whitewashing @Rs 1.75/sq. mtr. = Rs (189 x 1.75)
= Rs 330.75