class 7 Maths Chapter-11 Perimeter and Area

Exercise-11.1

Question 1:
The length and the breadth of a rectangular piece of land is 500 m by 300 m respectively.
Find:
(i) Its area
(ii) The cost of the land, if 1 m² of the land costs Rs. 10,000.

Answer:
It is given in the question that,
Length of rectangular piece of land = 500 m
Breadth of rectangular piece of land = 300 m
(i) We know that,
Area of rectangle = Length × Breadth
= 500 × 300
= 150000 m2
∴ Area of rectangular piece of land = 150000 m²
(ii) It is given in the question that,
Cost of 1 m² land = Rs 10,000
Hence,
Cost of 150000 m² land = 10000 × 150000
= Rs 1500000000

Question 2:
Find the area of a square park whose perimeter is 320 m.

Answer:
It is given in the question that,
Perimeter of square park = 320 m
We know that,
Perimeter of square park = 4 × Length of the side of park
320 = 4 × Length of the side of the park
∴ Length of side of park = 320/4
= 80 m
We also know that,
Area of square = (Side)²
= (80)²
= 6400 m²

Question 3:
Find the breadth of a rectangular plot of land. If its area is 440 m² and the length is 22 m.
Also find its perimeter.

Answer:
It is given in the question that,
Length of the rectangular plot of land = 22 m
Area of rectangular plot of land = 440 m²
We know that,
Area of rectangle = Length × Breadth
440 = 22 × Breadth
∴ Breadth = Area/Length
 =440/22
= 20 m
Breadth of the rectangular plot of land = 20 m
We know that:
Perimeter of rectangle = 2 (length + Breadth)
= 2 (22 + 20)
= 2 (42)
= 84 m
Hence, perimeter of rectangle = 84 m

Question 4:
The perimeter of a rectangular sheet is 100 cm. If the length is 35 cm, find its breadth. Also find the area.

Exercise-11.2

Exercise-11.3

Exercise-11.4

Question 1:
Tell what is the profit or loss in the following transactions.  Also find profit per cent or loss per cent in each case
(a) Gardening shears bought for Rs. 250 and sold for Rs. 325.
(b) A refrigerator bought for Rs. 12,000 and sold at Rs. 13,500.
(c) A cupboard bought for Rs. 2,500 and sold at Rs. 3,000.
(d) A skirt bought for Rs. 250 and sold at Rs. 150.

Answer:
(a) It is given in the question that,
Cost price of the product = Rs 250
Also,
Selling price of the product = Rs 325
Therefore,
Profit = Selling Price – Cost Price
  = 325 – 250
  = Rs 75

Selling price of the refrigerator = Rs 13,500

Therefore,

Profit = Selling Price – Cost Price

= 13,500 – 12,000

= Rs 1500

We know that,

(d) It is given in the question that,

Cost price of the skirt = Rs 250

Also,

Selling price of the skirt = Rs 150

Therefore,

Loss = Cost Price – Selling Price