You are allotted a rectangular room of a fixed height. You have decided to paint the three walls and put wallpaper on the fourth one. Walls can be painted at a cost of Rs. $10$ per meter and the wall paper can be put at the rate of Rs $20$ per meter for that specified height. What is the minimum cost at which you can achieve this covering for a $200$ square meter room?
- $400 \times \sqrt{3} $
- $400$
- $400 \times \sqrt{2}$
- $200 \times \sqrt{3}$
- $500$