Question

a room is 10 metre long 6 metre wide and 4 .2metre height .it has1 doors of 2.5 m into 1.5 m and one window of
dimension 1.5 m into 1 m find the cost of white washing the walls at rupees 2.50 per square metre

Answer 1

for room
Length ( L ) = 10m
wide ( B ) = 6m
height ( H) = 4.2 m

area of room = 2(LB + BH + HL)
= 2( 10 × 6 + 6 × 4.2 + 4.2 × 10)
= 2( 60 + 25.2 + 42)
= 2 × 127.2
= 254.4 m²

now,
area of door = Length × wide
here, for door ,
Length = 2.5 m
wide = 1.5 m
now, area of door = 2.5 × 1.5 = 3.75 m²

again find area of window ,
area of window = Length × wide
here , for window
Length = 1.5 m
wide = 1 m
now , area of window = 1.5 × 1 = 1.5 m²

now,
area of walls of room where we have to require washing = area of room - area of window - area of door
= 254.4 - 1.5 - 3.75
= 254.4 - 5.25
= 249.15 m²

now, total cost = area of walls of room where we have to require washing × rate of washing
= 249.15 × 2.5
=622.875 Rs