Question

the length breadth and height of a room is 5m 4m and 3m. the cost of white washing its four walls at the rate of rs 7.50 per m square.....options are - rs 110 rs 109 rs 220 rs 405......answer must be one of them​

Answer 1

$\underline{\underline{\sf \bold {Given :}}} </p><p></p><p>$

• Length,l = 5 m

• Breadth,b = 4 m

• Height,h = 3 m

• Cost of white washing of 1 m² = rs 7.50

$\underline{\underline{\sf \bold {To \: find \: out :}}} </p><p></p><p>$

Find the total Cost of white washing the walls ?

$\underline{\underline{\sf \bold {Formula \: used :}}} </p><p></p><p>$

$\boxed {\sf{ \star \: Area \: of \: four \: walls \: = 2h(l + b)}}$

$\underline{\underline{\sf \bold {Solution :}}} </p><p></p><p>$

We know that,

Area of four walls = 2h ( l + b )

= 2 × 3 ( 5 + 4 )

= 6 × 9

= 54 m²

Now,

Cost of white washing of 1 square m = Rs 7.50

Cost of white washing of 54 square m = Rs ( 7.50 × 54 )

Total cost of white washing the four walls = Rs 405

Answer 2

Length=5m

Breadth=4m

Height=3m

So we have to find LSA of the cuboid

LSA=2×height[length+breadth]

2×3m[5m+4m]

6m[9m]

54 metre square

Cost of white washing at metre square =Rs 7.50

Cost of white washing at 54 metresquare=Rs7.50×54

Rs 450

So,option 4 is correct