Question

The Length breadth and height of a room are 5m 4m and 3M respectively. Find the cost of white washing the walls of the room and the ceiling at the rate of ₹ 7.50 per metre square​

Answer 1

Given that:

l= 5m

b= 4m

h= 3m

TSA= 2hl+ 2bh+ lb (floor is not to be painted)

       = 2×3×5 + 2×4×3 + 5×4

       = 30+ 24+ 20

       = 74m²

COST OF WHITE WASHING= 74×7.5

                                               = Rs.555

Answer 2

Answer:The cost of white washing the four wslls and the ceiling of the cuboid shaped room is ₹ 555.

Step-by-step explanation: For a cuboid shaped room,

length (l)= 5 metre

breadth (b)= 4 metre

height (h)=3 metre

We know,

Total surface area of a cuboid = 2(lb+bh+lh)

                                                  =2(5*4+4*3+5*3)

                                                  =2(20+12+15)

                                                  =2(47)

                                                  =94 m^2

But, floor of room will not be white washed.

Thus, the area of the rectangular floor must be excluded.

Therefore,

Area of rectangular floor= l*b

                                        =5*4

                                        =20 m^2

Hence,

area of the walls and ceiling=area of the cuboid shaped room - area of floor

                                              =94-20

                                              =74 m^2

Thus, at the rate of 7.50 metre per square, the cost of white washing the ceiling and the four walls is as follows:

=74 * 7.50

=₹555