S.chand class 6 Mathematics Chapter 21 Exercise 21B

 Exercise 21B

Question 1

Which of the following closed plane figures are not polygons?

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Question 2

Which of the following figures are not polygons, and why? Give reasons.

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Question 3

For each polygon:

- write down the number of sides.

- name the polygon.

The first shape has 3 sides. It is a triangle.

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Multiple Choice Questions (MCQs)

Tick (✔) the correct option.

4. Which of the following is a regular polygon?

(a) Isosceles triangle

(b) Rectangle

(c) Rhombus

(d) Equilateral triangle

5.Name the polygon that best describes the given traffic sign 'STOP'

(a) pentagon

(c) octagon

(d) nonagon

6. Which of the following statements is sometimes false for a polygon?

(a) A polygon is a closed figure.

(c) Each side of a polygon intersects exactly (b) A polygon is made up of straight lines.

(d) A plane figure is a polygon.

RS Aggarwal solution class 8 chapter 21 Data Handling Exercise 21B

Exercise 21B

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Q1 | Ex-21B | Class 8 | RS AGGARWAL | chapter 21 | Data Handling

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Question 1:

The marks obtained by 40 students of a class in an examination are given below:

8, 47, 22, 31, 17, 13, 38, 26, 3, 34, 29, 11, 22, 7, 15, 24, 38, 31, 21, 35, 42, 24, 45, 23, 21, 27, 29, 49, 25, 48, 21, 15, 18, 27, 19, 45, 14, 34, 37, 34.
Prepare a frequency distribution table with equal class intervals, starting from 0−10 (where 10 not included).

Answer 1:

Arranging the given observations in ascending order, we get:

3, 7, 8, 11, 13, 14, 15, 15, 17, 18, 19, 21, 21, 21, 22, 22, 23, 24, 24, 25, 26, 27, 27, 29, 29, 31, 31, 34, 34, 34, 35, 37, 38, 38, 42, 45, 45, 47, 48, 49

Thus, the frequency distribution may be represented as shown below:

Marks	Tally marks	Frequency
0-10	|||	3
10-20	|||| |||	8
20-30	||||  |||| ||||	14
30-40	|||| ||||	9
40-50	|||| |	6
	Total	40

Q2 | Ex-21B | Class 8 | RS AGGARWAL | chapter 21 | Data Handling

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Question 2:

The electricity bills (in rupees) of 25 houses of a certain locality for a month are given below:
324, 700, 617, 400, 356, 365, 435, 506, 548, 736, 780, 378, 570, 685, 312, 630, 584, 674, 754, 776, 596, 745, 565, 763, 472.
Arrange the above data in increasing order and form a frequency table using equal class intervals, starting from 300−400, where 400 is not included.

Answer 2:

Arranging the given observations in increasing order, we get:
312, 324, 356, 365, 378, 400, 435, 472, 506, 548, 565, 570, 584, 596, 617, 630, 674, 685, 700, 736, 745, 754, 763, 776, 786

Thus, the frequency distribution may be represented as shown below:
 

Electricity bills (in Rupees)	Tally marks	Frequency
300-400	||||	5
400-500	|||	3
500-600	|||| |	6
600-700	||||	4
700-800	|||| ||	7
	Total	25

Q3 | Ex-21B | Class 8 | RS AGGARWAL | chapter 21 | Data Handling

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Question 3:

The weekly wages (in rupees) of 28 workers of a factory are given below:
668, 610, 642, 658, 668, 620, 719, 720, 700, 690, 710, 642, 672, 654, 692, 706, 718, 702, 704, 678, 615, 640, 680, 716, 705, 615, 636, 656.
Construct a frequency table with equal class intervals, taking the first of the class intervals as 610−630, where 630 is not included.

Answer 3:

Arranging the given observations in ascending order, we get:
610, 615, 615, 620, 636, 640, 642, 642, 654, 656, 658, 668, 668, 672, 678, 680, 690, 692, 700, 702, 704, 705, 706, 710, 716, 718, 719, 720

Thus, the frequency distribution may be represented as shown below:
 

Weekly wages (in Rupees)	Tally marks	Frequency
610-630	||||	4
630-650	||||	4
650-670	||||	5
670-690	|||	3
690-710	|||| ||	7
710-730	||||	5
	Total	28

Q4 | Ex-21B | Class 8 | RS AGGARWAL | chapter 21 | Data Handling

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Question 4:

The weekly pocket expenses (in rupees) of 30 students of a class are given below:
62, 80, 110, 75, 84, 73, 60, 62, 100, 87, 78, 94, 117, 86, 65, 68, 90, 80, 118, 72, 95, 72, 103, 96, 64, 94, 87, 85, 105, 115.
Construct a frequency table with class intervals 60−70 (where 70 is not included), 70−80, 80−90, etc.

Answer 4:

Arranging the given observations in increasing order, we get:
60, 62, 62, 64, 65, 68, 72, 72, 73, 75, 78, 80, 80, 84, 85, 86, 87, 87, 90, 94, 94, 95, 96, 100, 103, 105, 110, 115, 117, 118

Thus, the frequency distribution may be represented as given below:
 

Weekly pocket expenses (in Rupees)	Tally marks	Frequency
60-70	|||| |	6
70-80	||||	5
80-90	|||| ||	7
90-100	||||	5
100-110	|||	3
110-120	||||	4
	Total	30

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Q5 | Ex-21B | Class 8 | RS AGGARWAL | chapter 21 | Data Handling

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Question 5:

The daily earnings (in rupees) of 24 stores in a market was recorded as under:
715, 650, 685, 550, 573, 530, 610, 525, 742, 680, 736, 524, 500, 585, 723, 545, 532, 560, 580, 545, 625, 630, 645, 700.
Prepare a frequency table taking equal class sizes. One such class is 500−550, where 550 is not included.

Answer 5:

Arranging the given observations in increasing order, we get:
500, 524, 525, 530, 532, 545, 545, 550, 560, 573, 580, 585, 610, 625, 630, 645, 650, 680, 685, 700, 715, 723, 736, 742

Thus, the frequency distribution may be represented as given below:
 

Daily earnings (in Rupees)	Tally marks	Frequency
500-550	||||| ||	7
550-600	|||||	5
600-650	||||	4
650-700	|||	3
700-750	|||||	5
	Total	24

Q6 | Ex-21B | Class 8 | RS AGGARWAL | chapter 21 | Data Handling

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Question 6:

The heights (in cm) of 22 students were recorded as under:
125, 132, 138, 144, 142, 136, 134, 125, 135, 130, 126, 132, 135, 142, 143, 128, 126, 136, 135, 130, 130, 133.
Prepare a frequency distribution table, taking equal class intervals and starting from 125−130, where 130 is not included.

Answer 6:

Arranging the given observations in increasing order, we get 125, 125, 126, 126, 128, 130, 130, 130, 132, 132, 133, 134, 135, 135, 135, 136, 136, 138, 142, 142, 143 and 144.

Thus, the frequency distribution may be represented as given below:
 

Heights (in cm)	Tally marks	Frequency
125-130	||||	5
130-135	|||| ||	7
135-140	|||| |	6
140-145	||||	4
	Total	22