Question

a classroom is 7m long ,6m broad and 3.5 m high. the doors and windows occupy an area of 17m square. find the cost of white washing the walls at the rate of Rs 1.50 per m square.

Answer 1

dimensions of room =7×6×3.5 m
area of door and window =17 m^2
rate of white washing =Rs 1.50

c.s.a.of room = 2(l+b)h -area of door and window
=2(7+6)3.5 -17
=13×7 -17
=91 -17
= 74 m^2
cost of white washing walls = 1.50 ×74 =Rs 111

Answer 2

dimensions of room =7×6×3.5 m

area of door and window =17 m^2

rate of white washing =Rs 1.50

c.s.a.of room = 2(l+b)h -area of door and window

=2(7+6)3.5 -17

=13×7 -17

=91 -17

= 74 m^2

cost of white washing walls = 1.50 ×74 =Rs 111