Question

the size of a room 6m by 5m by 4m leaving one door of size 2m by 1m and two windows of size 1m by 60cm ,four walls were painted. how much would he charge at the rate of rupees 10per sq m

Answer 1

SA of walls =34.4m^2 so rate is equal to 10×34.4=344rupees

Answer 2

room-
length=6m breadth=5m heigth=4m
lateral surface area of room = 2(l+b)h
=2(6+5)4 = 2*4(11) = 8*11 = 88sq. m.
door-
length=2m breadth=1m
area of door = l*b = 2*1 = 2sq. m.
windows-
length=1m breadth=0.6m
area of 2 windows = 2*l*b = 2*1*0.6 = 1.2sq. m.
area to be painted =
area of room-(area of door+area of 2 windows)
88-(22+1.2) = 88-23.2 = 64.8sq. m.
cost of painting 1sq. m. = Rs.10
cost of 64.8sq. m. = 10*64.8 = Rs.648
hence the cost of painting four walls is Rs.648