Question

a classroom is 12 m long 10 m wide and 1.5 m hi it has two rows each 2 m long 1 m wide and 3 windows each 1.5 and 0.5 m find the cost of painting its four walls at 12 rupees per metre square ​

Answer 1

Answer:

Length of room = 12 m

Breadth of room = 10 m

Height of room = 1.5 m

Room is cuboid in shape. So,

Curved surface area of cuboid = 2h(1 +

b)

Substitute the known values in above

formula

=> 2 x 1.5(12 + 10)

=> 3(22)

=> 66 m²

Now,

Length of window = 1.5 m

Breadth of window = 0.5 m

So,

Area of 3 windows = 3(1 + b)

Substitute the known values in above

formula

=> 3(1.5 + 0.5)

=> 3(2)

=> 6 m²

Also,

Length of door = 2 m

Breadth of door = 1 m

Area of 2 doors = 2(1 + b)

=> 2(2 + 1)

=> 2(3)

=> 6 m²

Area of four walls without doors and windows = CSA of room - (Area of 3 windows + Area of 2 doors)

=> 66 - (6 + 6)

=> 66-12

=> 54 m²

Cost of painting the four walls at Rs.

per m²

12

=> 54 x 12

=> Rs. 648