Statistics Class-8 RS Aggarwal ICSE Goyal Brothers Prakashan Solutions Chapter-25. We provide step by step Solutions of Exercise / lesson-25 Statistics for ICSE Class-8  RS  Aggarwal Mathematics.

Our Solutions contain all type Questions of Exe-25 with Notes to develop skill and confidence. Visit official Website CISCE for detail information about ICSE Board Class-8 Mathematics.

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Notes on Statistics

Exe-25 ,

### Notes on Statistics

#### Introduction to Statistics

– A study dealing with the collection, presentation and interpretation and analysis of data is called as statistics

#### Data

• Facts /figures numerical or otherwise collected for a definite purpose is called as data.
• data collected first-hand data:- Primary
• Secondary data: Data collected from a source that already had data stored

#### Frequency

– The number of times a particular instance occurs is called frequency in statistics.

#### Ungrouped data

Ungrouped data is data in its original or raw form. The observations are not classified in groups.

#### Grouped data

In grouped data, observations are organized in groups

#### Class Interval

• The size of the class into which a particular data is divided.
•    E.g divisions on a histogram or bar graph.
• Class width = upper class limit – lower class limit

#### Regular and Irregular class interval

• Regular class interval: When the class intervals are equal or of the same sizes.
• E.g 0-10, 10-20, 20-30…..
• Irregular class interval: When the class intervals are of varying sizes.
• E.g 0-35, 35-45, 45-55,

#### Frequency table

– A frequency table or distribution shows the occurrence of a particular variable in a tabular form.

#### Sorting

• Raw data needs to be sorted in order to carry out operations.-
• Sorting ⇒ ascending order or descending order

#### Ungrouped frequency table

– When the frequency of each class interval is not arranged or organised in any manner

#### Grouped frequency table

– The frequencies of the corresponding class intervals are organised or arranged in a particular manner, either ascending or descending.

### Exe-25 ,Statistics Class-8 RS Aggarwal ICSE Goyal Brothers Prakashan Solutions

Question 1:

Arrange the following data in ascending order:
(i) 8, 3, 11, 15, 1, 7, 16, 25, 9, 4
(ii) 5.7, 9.2, 3.1, 4.6, 1.8, 10.4, 2.5, 0.9, 1.2.

Answer :

(i) Ascending order is

1, 3, 4, 7, 8, 9, 11, 15, 16, 25

(ii) Ascending order is

0.9, 1.2, 1.8, 2.5, 3.1, 4.6, 5.7, 9.2, 10.4.

Question 2:

Arrange the following data in descending order:
(i) 15, 3, 0, 11,7, 2, 23, 14, 29, 5, 1, 17.
(ii) 23, 4.6, 1.2, 0.4, 3.5, 9.7, 6.1, 4.8, 0.8, 1.0.

Answer :

(i) Descending order is
29, 23, 17, 15, 14, 11. 7, 5, 3, 2, 1, 0.
(ii) Descending order is
9.7, 6.1, 4.8, 4.6, 3.5, 2.3, 1.2, 1.0, 0.8, 0.4.

Question 3:

Construct a frequency table for each of the following data:
(i) 3, 2, 5, 4, 1, 3, 2, 2, 5, 3, 1, 2, 1, 1, 2, 2, 3, 4, 5, 3, 1, 2, 3.
(ii) 7, 8, 6, 5, 6, 7, 7, 9, 8, 10, 7, 6, 7, 8, 8, 9, 10, 5, 7, 8, 7, 6.
(iii) 152, 165, 172, 144, 135, 156, 175, 140, 132, 150, 153, 147.
(iv) 13, 25, 19, 16, 8, 30, 27, 6, 0, 34, 40, 11, 4, 17.

Answer :

(i)

(ii)

(iii)

(iv)

Question 4:

Fill in the blanks:
(i) Lower limit of the class interval 14-22 is……………
(ii) Upper limit of the class interval 16-25 is…………..
(iii) Class-size of the class interval 20-30 is…………..
(iv) the upper and lower limits of a class interval be 18 and 11 respectively, then the class-interval is ………….

(v) If the lower and upper limits of a class interval be 11:5 and 21-5 respectively, then the class-
interval is………………

Answer :

(i) 14

(ii) 25

(iii) 10

(iv) 11-18

(v) 11.5-21.5

Question 5:

The marks out of 50. obtained by 30 students of a class in an examination are given below:
40, 12, 46, 37, 17, 27, 30, 6, 2, 23, 19, 39, 25, 5, 33, 19, 21, 12, 41, 17, 12, 19, 17, 8, 10, 1, 9, 21, 13, 48
Arrange them in ascending order and present it as a grouped data. by taking class-intervals
0-10, 10-20, 20-30, 30-40, 40-50.

Answer :

In Ascending order :
1, 2, 5, 6, 8, 9, 10, 12, 12, 12, 13, 17, 17, 17, 19, 19, 19, 21, 21, 23, 25, 27, 30, 33., 17. 39, 40, 41, 46, 48.

Question 6:

The fine imposed (in rupees) on 40 pupils for being absent is given below :
18, 8, 12, 6, 8, 16, 12, 5, 23, 2, 16, 23, 2, 10, 20, 12, 9, 7, 0, 5, 3, 6, 27, 21, 19, 15, 20, 24, 2, 16, 14, 8, 23, 24, 10, 14, 3, 8, 11, 2.
Present the data in the form of frequency distribution table by taking class intervals 0-5, 5-10, 10-15, 15-20, 20-25.

Answer :

P. Q. The weights in grams of 50 oranges are as follows:
126, 86, 70, 92, 11, 136, 141, 111, 107, 80, 110, 104, 118, 131, 113, 82, 75, 204. 81, 108, 100, 123, 90, 78, 90, 115, 110, 98, 106, 99, 107, 84, 76, 186, 82, 125, 123, 195, 68, 130, 128, 129, 139, 187, 93, 119, 115, 107, 115, 75.

From the grouped frequency table by taking class-intervals.

60-80, 80-100, 100-120, 12-140, 140-160, 160-180, 180-200, 200-220.

Answer :

Question 7:

The weights (in kg) of 30 students are given below:
48, 55, 30, 43, 41, 36, 48, 37, 34, 38, 46, 42, 38, 52, 37, 34, 40, 42, 50, 37, 35, 46, 42, 43, 37, 39, 45, 48, 46.

Form the grouped frequency table by taking class-intervals 30-35, 35-40, 40-45, 45-50, 50-55.

Answer :

Question 8:

The daily income (in rupees) of 30 workers is given below:
83, 96, 91, 80, 97, 111, 90, 83, 112, 120, 103, 77, 82, 90, 70, 68, 89, 85, 78, 105, 94, 97, 90, 89, 102, 113, 90, 106, 70, 84.

Construct a frequency table using groups 65-75, 75-85, 85-95, 95-105, 105-115, 115-125.

Answer :

Question 9:

The heights of 45 students measured to the nearest centimeter are given below:

155, 166, 159, 161, 158, 154, 153, 159, 157, 152, 160, 157. 158, 170, 152, 151, 162, 164, 171, 154, 165, 161, 150, 168, 162, 154, 160, 170, 163, 164, 165, 169, 165, 155, 157, 158, 160, 161, 156, 153. 150, 165, 167, 169, 172.

Prepare a frequency table taking the class intervals
150-155, 155-160, 160-165, 165-170, 170-175.

Answer :

Question 10:

Complete the table given below:

Answer :

Class-mark of 25-30 = (25 + 30)/2

= 55/2

= 27.5

Question 11:

Complete the table given below:

Answer :

Class-mark of 26-30 = (26 + 30)/2

= 56/2

= 28

–: End of Statistics Class-8 RS Aggarwal Solutions :–

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