 Hi and welcome to the session. I am Neha and today I will help you with the following question. The question says, the floor of a building consists of 3000 tiles with a rhombus shape and each of its tile lengths are 45 cm and 30 cm in length. Find the total cost of polishing the floor if the cost per meter square is rupees 4. Before proceeding for the solution, let's recall area of rhombus. Area of rhombus is equal to 1 by 2 into D1 into D2 where D1 and D2 are the lengths of diagonals. This is the key idea for this question. Now let's see its solution. In question we are given that the floor consists of 3000 tiles with a rhombus in shape and the diagonals of one tile are 45 cm and 30 cm in length. So first of all let's find out the area of one tile. So for D1 that is the length of one diagonal that is 45 cm and D2 is equal to the length of second diagonal that is 30 cm. Therefore area of one tile is equal to 1 by 2 into D1 that is 45 cm into D2 that is 30 cm. Now here 2 and 30 will get cancelled by the common factor 2 and on simplifying this we will get 675 cm2. Now this is the area of one tile therefore area of 3000 tiles will be equal to 675 cm2 into 3000 that is equal to 0 cm2. Now we need to find the total cost of polishing the floor if the cost per meter square is rupees 4. Now we are given the cost in per area in cm2. So now we will change the area from cm2 to m2. Now we know that 1 cm is equal to 1 upon 100 m2 into 1 cm is equal to 1 upon 100 m2 is equal to so that means square will be equal to meter square will be equal to rupees 4 into 202.5 rupees 810 polishing the floor is rupees 810. In this session hope you must have understood the question.