A person has 20m 60m long electric wire and a water pipe of length 6m, and he requires 26m of electric wire and 21/2m long water pipe. How much will he spend on buying these if electric wire costs 25 rupees per m and water pipe costs 20 rupees per m?
Answers
1. Find the perimeters of the rectangles whose lengths and breadths are given below:
(i) 7 cm, 5 cm
(ii) 5 cm, 4 cm
(iii) 7.5 cm, 4.5 cm
Solution:
(i) We know that the perimeter of a rectangle = 2 (L + B)
It is given that L = 7 cm and B = 5 cm
So the perimeter of a rectangle = 2 (7 + 5) = 2 × 12 = 24 cm
(ii) We know that the perimeter of a rectangle = 2 (L + B)
It is given that L = 5 cm and B = 4 cm
So the perimeter of a rectangle = 2 (5 + 4) = 2 × 9 = 18 cm
(iii) We know that the perimeter of a rectangle = 2 (L + B)
It is given that L = 7.5 cm and B = 4.5 cm
So the perimeter of a rectangle = 2 (7.5 + 4.5) = 2 × 12 = 24 cm
2. Find the perimeters of the squares whose sides are given below:
(i) 10 cm
(ii) 5 m
(iii) 115.5 cm
Solution:
(i) We know that the perimeter of a square = 4 × Length of one side
It is given that L = 10 cm
So the perimeter of a square = 4 × 10 = 40 cm
(ii) We know that the perimeter of a square = 4 × Length of one side
It is given that L = 5 m
So the perimeter of a square = 4 × 5 = 20 m
(iii) We know that the perimeter of a square = 4 × Length of one side
It is given that L = 115.5 cm
So the perimeter of a square = 4 × 115.5 = 462 cm
3. Find the side of the square whose perimeter is:
(i) 16 m
(ii) 40 cm
(iii) 22 cm
Solution:
(i) We know that side of a square = perimeter/ 4
It is given that perimeter = 16 m
So the side of the square = 16/4 = 4 m
(ii) We know that side of a square = perimeter/ 4
It is given that perimeter = 40 cm
So the side of the square = 40/4 = 10 cm
(iii) We know that side of a square = perimeter/ 4
It is given that perimeter = 22 cm
So the side of the square = 22/4 = 5.5 c
4. Find the breadth of the rectangle whose perimeter is 360 cm and whose length is
(i) 116 cm
(ii) 140 cm
(iii) 102 cm
Solution:
We know that the perimeter of a rectangle = 2 (L + B)
So the breadth of the rectangle = perimeter/2 – length
(i) It is given that perimeter = 360 cm and length = 116 cm
So the breadth of the rectangle = 360/2 – 116 = 180 – 116 = 64 cm
(ii) It is given that perimeter = 360 cm and length = 140 cm
So the breadth of the rectangle = 360/2 – 140 = 180 – 140 = 40 cm
(iii) It is given that perimeter = 360 cm and length = 102 cm
So the breadth of the rectangle = 360/2 – 102 = 180 – 102 = 78 cm
. A rectangular piece of lawn is 55 m wide and 98 m long. Find the length of the fence around it.
Solution:
The dimensions of lawn are
Breadth = 55 m
Length = 98 m
We know that
Perimeter of lawn = 2 (L + B)
By substituting the values
Perimeter of lawn = 2 (98 +55)
So we get
Perimeter of lawn = 2 × 153 = 306 m
Hence, the length of the fence around the lawn is 306 m.
6. The side of a square field is 65 m. What is the length of the fence required all around it?
Solution:
It is given that
Side of a square field = 65 m
So the perimeter of square field = 4 × side of the square
By substituting the values
Perimeter of square field = 4 × 65 = 260 m
Hence, the length of the fence required all around the square field is 260 m.
7. Two sides of a triangle are 15 cm and 20 cm. The perimeter of the triangle is 50 cm. What is the third side?
Solution:
It is given that
First side of triangle = 15 cm
Second side of triangle = 20 cm
In order to find the length of third side
We know that perimeter of a triangle is the sum of all three sides of a triangle
So the length of third side = perimeter of triangle – sum of length of other two sides
By substituting the values
Length of third side = 50 – (15 + 20) = 15 cm.
Hence, the length of third side is 15 cm.
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Step-by-step explanation:
ATQ , he doesn't need to buy what he already have
so we have ,
wire required= 26m
pipe required = (21/2)m
cost of wire = ₹25/m
therefore cost of 26m wire= 26m×₹25/m= ₹650
and cost of pipe=₹ 20/m
cost of (21/2)m pipe= (21/2)×₹20= ₹210
total cost = ₹650+₹210= ₹860