# 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. Find the total cost of polishing the floor, if the cost per m² is ₹ 4

**Solution:**

Let ABDC be a rhombus as shown below with AD and BC as the diagonals.

Let BC = 30 cm, AD = 45 cm

Area of rhombus ABDC = Area of ΔABC + Area of ΔDCB

= 1/2 × (BC × AO) + 1/2 × (BC × OD)

= 1/2 × BC × (AO + OD)

= 1/2 × BC × AD

= 1/2 × 30 cm × 45 cm

= 675 cm²

Area of each tile = 675 cm²

Area covered by 3000 tiles = (675 × 3000) cm² = 2025000 cm² = 202.5 m²

Given that the cost of polishing is Rs. 4 per m²

Cost of polishing for 202.5 m² area = Rs. 4 × 202.5 = Rs. 810

**☛ Check: **NCERT Solutions for Class 8 Maths Chapter 11

**Video Solution:**

## 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. Find the total cost of polishing the floor, if the cost per m² is ₹ 4

Class 8 Maths NCERT Solutions Chapter 11 Exercise 11.2 Question 7

**Summary:**

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. If the cost per m² is ₹ 4, the total cost of polishing the floor is ₹ 810.

**☛ Related Questions:**

- Mohan wants to buy a trapezium shaped field. Its side along the river is parallel to and twice the side along the road. If the area of this field is 10500 m2 and the perpendicular distance between the two parallel sides is 100 m, find the length of the side along the river.
- Top surface of a raised platform is in the shape of a regular octagon as shown in the figure. Find the area of the octagonal surface.
- There is a pentagonal shaped park as shown in the figure. For finding its area Jyoti and Kavita divided it in two different ways. Find the area of this park using both ways. Can you suggest some other way of finding its area?
- Diagram of the adjacent picture frame has outer dimensions = 24 cm × 28 cm and inner dimensions 16 cm × 20 cm. Find the area of each section of the frame, if the width of each section is same.

visual curriculum