A classroom is 7 m long, 6.5 m wide and 4 m high. It has one door meas

1.	A classroom is 7 m long, 6.5 m wide and 4 m high. It has one door measuring 3 m x 1.4 m and three windows,each measuring 2 m x 1 m. The interior walls are to be white washed. The contractor charges 7.25 per sq. m.Find the cost of white washing the interior walls of a classroom.
Answer» length of classroom = 7 m width of classroom = 6.5 m and height of classroom = 4 m ∴ Area of the four walls of room = 2h(l+b) = 2 × 4 (7 + 6.5) m^2 = 8 (13.5) m^2 = 108 m^2 Now, dimension of door = 3 m × 14 m ∴ Area of door = 3 × 14 m2= 42 m2 Dimension of 1 window = 2m × 1m ∴ Area of 3 windows = 3 × [ 2 × 1m2] = 6 m2 Area coloured = Area of 4 walls of room – Area of door – Area of 3 window = 108 – 42 – 6 = 60 m2 Cost of colour washing for 1m2= Rs 7.25Cost of colour washing for 60 m2 60 × Rs 7.25 = Rs 435

A classroom is 7 m long, 6.5 m wide and 4 m high. It has one door measuring 3 m x 1.4 m and three windows,each measuring 2 m x 1 m. The interior walls are to be white washed. The contractor charges 7.25 per sq. m.Find the cost of white washing the interior walls of a classroom.

Answer»

length of classroom = 7 m

width of classroom = 6.5 m and

height of classroom = 4 m

∴ Area of the four walls of room = 2h(l+b)

= 2 × 4 (7 + 6.5) m^2

= 8 (13.5) m^2

= 108 m^2

Now, dimension of door = 3 m × 14 m

∴ Area of door = 3 × 14 m2= 42 m2

Dimension of 1 window = 2m × 1m

∴ Area of 3 windows = 3 × [ 2 × 1m2] = 6 m2

Area coloured = Area of 4 walls of room – Area of door – Area of 3 window

= 108 – 42 – 6 = 60 m2

Cost of colour washing for 1m2= Rs 7.25Cost of colour washing for 60 m2 60 × Rs 7.25 = Rs 435