The floor of a building consists of 3000 tiles which are rhombus shaped and each of its diagonals are 45 cm and 30 cm in length.

Here, d’ = 45 cm and d’’= 30 cm

∵ Area of one tile = 1/2 d’ × d’’

= 1/2 × 45 × 30

= 675 cm²

∴ Area of 3000 tiles= 675 × 3000 = 2025000 cm²

= 202.50 m² ----------(∵ 1m² = 10000cm²)

∵ Cost of polishing the floor per sq. meter = 4

∴ Cost of polishing the floor per 202.50 sq. meter = 4 × 202.50 = 810

Hence the total cost of polishing the floor is Rs810