A carpet of size 5 m × 2 m has 25 cm wide red border. The inner part of the carpet is blue in colour (Fig. 9.56). Find the area of blue portion. What is the ratio of areas of red portion to blue portion?
Solution:
It is given that
Size of carpet = 5 m × 2m
Width of border = 25 cm = 25/100 m = 0.25 m
Area of carpet ABCD = AB × BC
Substituting the values
= 5 × 2
= 10 m²
Length of inner blue portion EF = AB - (2 × 0.25 cm)
Substituting the values
= 5 - 0.50
= 4.5 m
Breadth of inner blue portion FG = BC - (2 × 0.25)
Substituting the values
= 2 - 0.25
= 1.5 m
Area of blue portion = Area of rectangle EFGH = EF × FG
Substituting the values
= 4.5 × 1.5
= 6.75 m²
Area of red portion = Area of ABCD - Area of EFGH
Substituting the values
= 10 - 6.75
= 3.25 m²
We know that
Ratio of areas of red portion to blue portion = 3.25: 6.75
= 13: 27
Therefore, the area of the blue portion is 6.75 m² and the ratio of areas of red portion to blue portion is 13: 27
✦ Try This: A circular pond is surrounded by a 3 m wide circular path. If outer circumference of circular path is 66 m, find the inner circumference of the circular path. Also find area of the path.
☛ Also Check: NCERT Solutions for Class 7 Maths Chapter 11
NCERT Exemplar Class 7 Maths Chapter 9 Problem 111
A carpet of size 5 m × 2 m has 25 cm wide red border. The inner part of the carpet is blue in colour (Fig. 9.56). Find the area of blue portion. What is the ratio of areas of red portion to blue portion?
Summary:
A carpet of size 5 m × 2 m has 25 cm wide red border. The inner part of the carpet is blue in colour (Fig. 9.56). The area of blue portion is 6.75 m². The ratio of areas of red portion to blue portion is 13: 27
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