New Learning Composite Mathematics Class 5 S.K. Gupta Anubhuti Gangal Perimeter and Area Chapter 17B Solution
New Learning Composite Mathematics Class 5 S.K. Gupta Anubhuti Gangal Perimeter and Area Chapter 17B Solution by Expert Math Teacher.
Self practice 17B
1) Complete the table for the area of rectangles.
(a) (b) (c) (d) (e)
Length |
40 cm | 0.12 m | 11 mm | 12.5 cm | 25 mm |
Width | 18 cm | 10 m | 7 mm | 20 cm |
60 mm |
Ans:
a) Area of rectangle = length × breadth = 40 × 18 sq cm = 720 sq cm
b) Area of rectangle = length × breadth = 0.12 × 10 sq m = 1.2 sq m
c) Area of rectangle = length × breadth = 11 × 7 sq mm = 77 sq mm
d) Area of rectangle = length × breadth = 12.5 × 20 sq cm = 250 sq cm
e) Area of rectangle = length × breadth = 25 × 60 sq mm = 1500 sq mm
2) By counting squares, find the area of each shape. Each side of small square = 1 cm
(a)
Ans: Number of full squares = 29
Number of half squares = 4
∴ Total number of squares = 29 + 4×(1/2) = 31
Area of one square = 1 sq cm
Area of the shape = 31 sq cm
(b)
Ans: Number of full squares = 22
Number of half squares = 4
∴ Total number of squares = 22 + 4×(1/2) = 24
Area of one square = 1 sq cm
Area of the shape = 24 sq cm
(c)
Ans: Number of full squares = 18
Number of half squares = 2
∴ Total number of squares = 18 + 2×(1/2) = 19
Area of one square = 1 sq cm
Area of the shape = 19 sq cm
3) Calculate area of each of the objects shown below.
a)
Ans:
The length of the given object is 9 cm and breadth is 6 cm.
So the area of the object is = length × breadth =9×6 sq cm = 54 sq cm
b)
Ans:
The length of the given object is 11 cm and breadth is 8.5 cm.
So the area of the object is = length × breadth =11×8.5 sq cm = 93.5 sq cm
c)
Ans:
The length of the given object is 4.7 m and breadth is 3.2 m.
So the area of the object is = length × breadth =4.7×3.2 sq m =15.04 sq m
4) Find the area of each of the rectangle whose dimensions are given below.
a) 5 cm by 3 cm
Ans: Area of rectangle = length × breadth = 5 × 3 sq cm = 15 sq cm
b) 8 cm by 5 cm
Ans: Area of rectangle = length × breadth = 8 × 5 sq cm = 40 sq cm
c) 22 cm by 10 cm
Ans: Area of rectangle = length × breadth = 22 × 10 sq cm = 220 sq cm
d) 28 cm by 23 cm
Ans: Area of rectangle = length × breadth = 28 × 23 sq cm = 644 sq cm
e) Length = 1 m 25 cm, Width = 70 cm
Ans: Length = 1.25 m width = 0.7 m
Area of rectangle = length × breadth = 1.25 × 0.7 sq m = 0.875 sq m
5) Find the area of the square whose one side is
a) 2 cm
Ans: Area of the square = side2 = 22 sq cm = 4 sq cm
b) 15 cm
Ans: Area of the square = side2 = 152 sq cm = 225 sq cm
c) 13 cm
Ans: Area of the square = side2 = 132 sq cm = 169 sq cm
d) 1.2 m
Ans: Area of the square = side2 = 1.22 sq m = 1.44 sq m
e) 2.5 cm
Ans: Area of the square = side2 = 2.52 sq cm = 6.25 sq cm
f) 27 m
Ans: Area of the square = side2 = 272 sq m = 729 sq m
g) 11.5 km
Ans: Area of the square = side2 = 11.52 sq km = 132.25 sq km
h) 100 m
Ans: Area of the square = side2 = 1002 sq m = 10000 sq m
i) 4(1/2) m
Ans: Area of the square = side2 = 4.52 sq cm = 20.25 sq cm
6) Which square unit would you use to measure the area of the following?
a) A page of this book – sq cm
b) The classroom Floor – sq m
c) A Stamp – sq mm
d) India – sq km
e) The blackboard – sq m
f) An insect’s wing – sq mm
g) The Indian Ocean – sq km
h) A basketball court – sq m
7) Tick (✓) the best estimate for the area.
a) An envelope i) 200 cm2 (✓) ii) 200 mm2 iii) 200 m2
b) A page of a newspaper i) 2640 mm2 ii) 2640 cm2 (✓) iii) 2640 m2
8) What is the area of the dial of a watch that is 25 mm long and 23 mm wide?
Ans:
Length of the dial = 25 mm and width of the dial = 23 mm
Area of rectangle = length × breadth = 25 × 23 sq mm = 575 sq mm
9) Compare the areas of a square of side 15 cm and a rectangle 11 cm by 8 cm. Which figure has greater area and by how much?
Ans:
Area of a square of side 15 cm is = 152 sq cm = 225 sq cm
Area of the rectangle of 11 cm by 8 cm = 11 × 8 sq cm. = 88 sq cm
The area of the square is greater than the rectangle by 137 sq cm.
10) A rectangular park measures 500 m by 100 m and a square field has a 220 m side.
a) Do the two parks have the same area?
b) Which park requires more fencing and by how much more? [hint: Length of fencing = Perimeter = Sum of all sides]
Ans: The area of the rectangular park = 500 × 100 sq m = 50000 sq m
The area of the square park = 2202 sq m = 48400 sq m
a) No, the areas of the two parks are not same.
b) Perimeter of the rectangular park is = 2 × (500+100) m = 1200 m
Perimeter of the square park is = 4×220 m = 880 m
The perimeter of the rectangular park is greater than the square park.
So the rectangular park will require more fencing by 320 meters.
11) Find the length of the rectangle whose
a) Area = 40 sq cm and breadth = 16 cm
Ans: Area of rectangle = length × breadth
Or, 40 = length × 16
Or, length = 2.5
The length of the rectangle is 2.5 cm
(b) Area = 1800 sq cm and breadth = 36 cm
Ans: Area of rectangle = length × breadth
Or, 1800 = length × 36
Or, length = 50
The length of the rectangle is 50 cm
12) Find the breadth of the rectangle whose
a) Area = 221 cm2 and length = 17 cm
Ans: Area of rectangle = length × breadth
Or, 221 = 17 × breadth
Or, breadth = 13
The breadth of the rectangle is 13 cm
b) Area = 100000 m2 and length = 1000 m
Ans: Area of rectangle = length × breadth
Or, 100000 = 1000 × breadth
Or, breadth = 100
The breadth of the rectangle is 100 m
13) Find the Perimeter of a rectangle whose
a) Area = 360 cm2, breadth = 6 cm
Ans: We know that
Area of rectangle = length × breadth
Or, 360 = length × 6
Or, length = 60
The length of the rectangle is 60 cm
The perimeter of the rectangle is 2×(60+6) cm = 132 cm
b) Area = 480 m2, breadth = 16 m
Ans: We know that
Area of rectangle = length × breadth
Or, 480 = length × 16
Or, length = 30
The length of the rectangle is 30 cm
The perimeter of the rectangle is 2×(30+16) cm = 92 cm
c) Area = 19(17/21) sq mm, length = 3(5/7) mm.
Ans: Area of the rectangle = 19(17/21) sq mm = 416/21 sq mm and
Length = 3(5/7) mm = 26/7 mm
We know that,
Area of rectangle = length × breadth
Or, 416/21 = length × 26/7
Or, length = 16/3 = 5(1/3)
The length of the rectangle is 5(1/3) mm
The perimeter of the rectangle is 2×[(16/3)+(26/7)] cm = 18(2/21) mm
Hey Champ: Do You miss Exercise 17A Solution?