Question

The dimensions of room are(9m×8m×6.5m). It has one door of dimensions (2m×1.5m) and two windows , each of dimensions (1.5m×1m). Find the cost of whitewashing the walls at Rs.6.40 per square metre​

Answer 1

if not to colour the floor and top then

lateral surface area of room =2h(b+l)

h=6.5,l=9,b=8

therefore,2×6.5(9+8)

13×17

221m^2

and leaving door and window then

area of door=2×1.5=3

and two windows=2×1.5×1=3

therefore, total=221-3-3=215

cost=215×6.40

=1376RS

HOPE IT HELPS......

Answer 2

Dimensions of a room are (9m×8m×6.5m).

Area of the room = 2(l+b)×h

= 2(9+8)×6.5 m²

= 2×17×6.5 m²

= 221m²

Area of door = (2m×1.5m)m²

= 3m²

Area of each window = (1.5m×1m)m²

= 1.5m²

Area of two windows = (1.5×2)m²

= 3m²

Total area of door and windows

= (3+3)m²

= 6m²

Area of the four walls = (221-6)m²

= 215m²

Cost of whitewashing the walls at ₹6.40 per square metre

= ₹(215×6.40)

= ₹1,376

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