Question

The length breadth and height of a room are 5m,4m,and 3mrespectively . find the cost of white washing the walls of the room and the ceiling at the rate of RS 7.50

Answer 1

Total surface area of room = 2(lb+bh+lh)
= 2(5×4+4×3+5×3)
= 94m^2
surface area of floot = l×b = 5×4=20m^2
therfore area of walls and ceiling = 94m^2 - 20m^2 = 74m^2
now cost of white washing walls and ceiling = Rs 7.50 × 74= Rs 555

Answer 2

We know that Area of 4 walls = 2h(l + b)

                                                  = 2 * 3(4 + 5)

                                                  = 54 sq.m

Area of ceiling = l * b

                         = 5 * 4

                         = 20 sqm

Total area = 54 + 20

                  = 74 sqm

Cost of whitewashing 7.50 sqm = 7.50 * 74

                                                     = 555.


Hope this helps!