A door of length 2 m and breadth 1 m is fitted in a wall. The length of the wall is 4.5 m and the breadth is 3.6 m (Fig11.6). Find the cost of white washing the wall, if the rate of white washing the wall is ₹ 20 per m².

Solution:

Length of the wall = 4.5 m

Breadth of the wall = 3.6 m

Area of the wall = Length × Breadth

= 4.5 m × 3.6 m

= 16.2 m²

Length of the door = 2 m

Breadth of the door = 1 m

So, area of the door = Length × Breadth

= 2 m × 1 m

= 2 m²

Area of the wall for whitewash = Area of the wall - Area of door

= 16.2 m² - 2 m²

= 14.2 m²

The rate of whitewashing the wall = Rs. 20 per m²

The cost of whitewashing 14.2 m² = 14.2 × Rs. 20 = Rs. 284

☛ Check: NCERT Solutions for Class 7 Maths Chapter 11

Video Solution:

A door of length 2 m and breadth 1 m is fitted in a wall. The length of the wall is 4.5 m and the breadth is 3.6 m (Fig11.6). Find the cost of white washing the wall, if the rate of white washing the wall is ₹ 20 per m²

Class 7 Maths NCERT Solutions Chapter 11 Exercise 11.1 Question 8

Summary:

A door of length 2 m and breadth 1 m is fitted in a wall. The length of the wall is 4.5 m and the breadth is 3.6 m. ₹ 284 is the cost of whitewashing the wall, if the rate of white washing the wall is ₹ 20 per m².

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