Question

the cost of repairing of four walls of a room at rupees 1.5 per metre square is rupees 324. the height of the room is 4.5m . if the ratio of length and breadth of a room is 5:3, fibd them.

Answer 1

$\Longrightarrow{\boxed{\bold{Answer: 15\:m\:and\:9\:m }}}$

$\textbf{\underline{Step-by-step explanation :- }}$

In order to understand trick of question, remember that when you have area and the cost of per sq. m then how you take out total cost?

Yes, by multiplying area and per unit area cost and we get total cost.

Area of 4 walls × Rs 1.5 per m² = Rs 324

Area of 4 walls = 324/1.5 m²

Area of 4 walls = 216 m²

$\textsf{Area of 4 walls of cuboidal room}$

$\textsf{= 2( l + b )h}$

216 = 2( l + b )h

216 = 2( l + b )4.5 m

24 m = ( l + b )

l : b = 5 : 3

So, let l = 5x and b = 3x

24 = 5x + 3x

24 = 8x

24/8 = 3 = x

$\bold{\underline{So\:length = 5 \times3\:m = 15\:m}}$
$\bold{\underline{And\:breadth = 3 × 3\:m = 9\:m}}$