Question

The volume of a square room of highest 5m is 180m^3.find the cost of painting its 4 walls at the rate of Rs. 10 per meter​

Answer 1

Let x be the width of the room and y its height.

The cost of painting the walls is Rs 640 at Rs 5 per square metre. That’s an area of 640 / 5 = 128 sq m for the four walls.

The total area of the walls is 4xy. From the above, this is equal to 128 sq m, so each wall has an area of xy = 32 sq m (1).

The volume of the room is yx^2 which we are told is 256 cu m (2).

Dividing (1) into (2) gives x = 8 metres.

Substituting in (1) gives y = 4 metres. Answer.