question_answer 12)

                The floor of a building consists of 3,000 tiles which are rhombus shaped and each of its diagonals are 45 cm and 30 cm in length. Find the total cost of polishing the floor, if the cost per \[{{m}^{2}}\] is Rs 4.

Answer:

                Area of a tile \[=\frac{1}{2}\times {{d}_{1}}\times {{d}_{2}}\] \[=\frac{1}{2}\times 45\times 30\] \[=675\,c{{m}^{2}}\] \[\therefore \]  Area of the floor \[=657\,\times 3,000\,c{{m}^{2}}\] \[=20,\,25,000\,c{{m}^{2}}\] \[=\frac{20,25000}{100\times 100}{{m}^{2}}\] \[=202.50\,{{m}^{2}}\]                 The cost of polishing per \[{{m}^{2}}=\text{Rs}\,4\] \[\therefore \]  Total cost of polishing the floor \[=202\,.50\times 4\] = Rs 810.