A class room is 7m long, 6.5m wide and 4m high. It has one door 3m ×

1.	A class room is 7m long, 6.5m wide and 4m high. It has one door 3m × 1.4m and three windows each measuring 2m × 1m The interior walls are to be color-washed. The contractor charges Rs. 15per sq. m. Find the cost of colour washing.
Answer» l = 7m, n = 6.5m and h = 4m ∴ Area of the room = 2( l + b)h = 2(7 + 6.5) 4 = 108m² Area of door = 3 × 1.4 = 4.2m² Area of one window = 3 × 2 = 6m² ∴ Area of 3 windows = 3 × 2 = 6m² ∴ Area of the walls of the room to be colour washed = 108 - (4.2 + 6) = 108 - 10.2 = 97.8m² ∴ Cost of colour washing @ Rs. 15 per square metre = Rs. 97.8 × 15 = Rs. 1467.

A class room is 7m long, 6.5m wide and 4m high. It has one door 3m × 1.4m and three windows each measuring 2m × 1m The interior walls are to be color-washed. The contractor charges Rs. 15per sq. m. Find the cost of colour washing.

Answer»

l = 7m, n = 6.5m and h = 4m

∴ Area of the room = 2( l + b)h = 2(7 + 6.5) 4 = 108m²

Area of door = 3 × 1.4 = 4.2m²

Area of one window = 3 × 2 = 6m²

∴ Area of 3 windows = 3 × 2 = 6m²

∴ Area of the walls of the room to be colour washed = 108 - (4.2 + 6)

= 108 - 10.2 = 97.8m²

∴ Cost of colour washing @ Rs. 15 per square metre = Rs. 97.8 × 15 = Rs. 1467.