Question

the Length breadth and height of a room are 5 M ,4 m and 3 M respectively find the cost of whitewashing the walls of the room and the ceiling at the rate rupees 7.50 per metre square

Answer 1

curved surface area of room =
$2h(l + b)$
2*3(5+4)

6(9)

54 m square.

now, area of ceiling.= l*b
= 5*4=20 m square.

so, total area we want = 54+20=74 m square.

now, cost of white washing per metre square=7.50
cost for 74 m. square= 7.50*74 = 555 rupees

Answer 2

Step-by-step explanation:

Length (l) of room = 5m

Breadth (b) of room = 4m

Height (h) of room = 3m

It can be observed that four walls and the ceiling of the room are to be white washed.

Total area to be white washed = Area of walls + Area of ceiling of room

= 2lh+2bh+lb

= [2×5×3+2×4×3+5×4]

= (30+24+20)

= 74

Area = 74 m2

Also,

Cost of white wash per m2 area = Rs.7.50 (Given)

Cost of white washing 74 m2 area = Rs. (74×7.50)

= Rs. 555