The sum of the dimensions of a room (i.e. length, breadth and height) is 24 metres and its length, breadth and height are in the ratio of 8…

Solution
Let the dimension of the room be $8x , 7x , 5x$ metres
Acc. to ques, => $8x + 7x + 5x = 24$
=> $x = \frac{24}{20} = 1.2$ metres
Curved surface area of the room = $2 h (l + b)$

= $2 \times 5x \times (8x + 7x) = 10x \times 15x$
= $150 (x)^2 = 150 \times (1.2)^2$
= $150 \times 1.44 = 216 m^2$
$\therefore$ Total cost incurred on painting only the four walls of the room = $12 \times 216$
= $Rs. 2,592$