Question

A room is 7 m long, 5 m wide and 4 m high. Find the cost of white-washing its four walls at the rate of Rs 40 per square meter

Answer 1

Answer:

Dimensions of the room: length-7m, width-6.5m, height-4m.

Area of four walls=[2h(l+b)]

=[2x4(7+6.5)]

=(8x13.5)

=108m sq.

area of one window =3mx1.42

=4.2m sq.

area of three windows =3(2mx1m)

=6m sq.

total area of windows =(4.2+6)m sq.

=10.2m sq.

Area for whitewashing =(108-10.2)m sq.

=97.8m sq.

cost of 1 m sq. white washing = 3.50rupee =

cost of 97.8m sq. white washing=3.50x 97.8 =342.3 rupees

Answer 2

Given :

• Length of room = 7 m
• Breadth of room = 5 m
• Height of room = 4 m

______________________________

To Find :

• Cost of white washing ita four walls at the rate of ₹ 40 per m²

______________________________

Solution :

★ C.S.A of room = 2h ( L + B )

→ C.S.A = 2 × 4 ( 7 + 5 )

→ C.S.A = 8 × 12

→ C.S.A = 96 m²

Cost of 1 m² white washing = ₹ 40

Cost of 245 m² white washing = 40 × 96 = 3840

∴ Cost of white washing ita four walls is ₹ 3840