Question

the length breadth and height of a rectangular room is 10m 8m and 5m respectively find the cost of plastering its wall and ceiling at rs 35 per square metre​

Answer 1

Rs 9100

SOLUTION

$length \: breadth \: and \: height \: of \: \\ room \: respectively \: are \: 10m \: 8m \: \\ 5m.$

$area \: of \: four \: walls \: of \: room \\ = 2h(l + b)$

$= 2 \times 5m(10m + 8m)$

$= 10m(18m)$

$= {180m}^{2}$

$area \: of \: the \: celling = l \times b$

$= 10m \times 8m$

$= {80m}^{2}$

$Total \: area \: of \: the \: four \: walls \\ and \: the \: ceiling \: of \: the \: room$

$= {180m}^{2} + {80m}^{2}$

$= {260m}^{2}$

$cost \: of \: plastering \: its \: wall = 35 \: rupees \: per \: {m}^{2}$

$total \: cost \: of \: plastering \: its \: wall$

$= 260 {m}^{2} \times 35 \: rupees \\ = 9100 \: rupees$

Answer 2

Step-by-step explanation:

Given, length of the room (l) = 10 m

Breadth of the room (b) = 8m

Height of the room (h) = 5m

And the cost of plastering = Rs. 35perm2

Therefore, the area of the walls = 2h(l+b)

= 2×5×(10+8) = 10×(18) = 180 m2

Area of the ceiling = lb = 10×8 =  80m2

Area of the room = 180+80= 260m2

Hence, the cost of plastering = 260×35= Rs 139,100