Notes on Statistics | Grade 7 > Compulsory Maths > Statistics | KULLABS.COM

Statistics

  • Note
  • Things to remember
  • Videos
  • Exercise
  • Quiz

Collection of data - Review

1 , 5, 6 ,5 ,8 ,7 ,5 ,10 ,0 , 2

1 ,2 , ,3,10 ,22, 8 ,7 ,9 ,15

The above are the marks obtain by the students of class 7 in math in dictation . The numerical figures are called data. Statistics is a branch of mathematically related with the collection of different thing which is shown by figures . It analysis the data. The data should be always shown proper order so that it will be easier to get the important and necessary information for which they are collected . The data are always arranged in ascending or descending order , which is known as a proper order.

The data which arranged properly are called arrayed data. If the data are not arranged properly then they are said raw data . Data are always can be present in a bar graph or in a line graph.

8 6 7 9 8 6 7 8

8 6 8 8 7 8 7 9

( Raw Data)

6 6 6 7 7 7 7 8

8 8 8 8 8 8 9 9

( Arrayed Data)

Here ,

  • Rs 6 is repeated three times. So , its frequency is 3.
  • Rs 7 is repeated four times . So, its frequency is 4.
  • Rs 8 is repeated seven times . So , its frequency is 7.
  • Rs 9 is repeated two times . So , its frequency is 2.
Wages (in Rs ) Tally marks Frequency
6 ||| 3
7 |||| 4
8 \(\enclose{horizontalstrike}{||||}\) || 7
Total 14

The data and their frequencies can be shown in the table called frequency table . So, the above wages of 14workers in the frequency table . It is the system of showing frequencies by using diagonal lines grouped in five when each time five is reached , there is a horizontal line is drawn with the tally marks to make a group of five . For example :

1 |
2 | |
3 |||
4 ||||
5 \(\enclose{horizontalstrike}{||||}\)
6 \(\enclose{horizontalstrike}{||||}\) |
7 \(\enclose{horizontalstrike}{||||}\) ||
8 \(\enclose{horizontalstrike}{||||}\) |||
9 \(\enclose{horizontalstrike}{||||}\) ||||
10 \(\enclose{horizontalstrike}{||||}\) \(\enclose{horizontalstrike}{||||}\)

Bar graph

There are mainly two types of a bar graph . They are described below :

Simple bar graph : The data which is presented single or the graph which is drawn to present single type of data is called simple bar graph . In a simple bar, data are equally wide . The height of the bars represents the frequency at the data.

source :illuminations.nctm.org Fig : Bargraph
source :illuminations.nctm.org
Fig : Bargraph
  • Construct the bars of the same width and at equal distance.
  • Decide how wide the bars will be and how much space you will leave between them.
  • Choose a suitable scale to represent the whole data . Mention the frequencies in the y-axis.

Multiple bar graph : Multiple bar graph is drawn to or more than two related components of the given data.

Average ( or mean )

The single number which represents the central value of a set of data is known as average . It indicated or show the quality of the data . It is calculated by adding them together and dividing the sum by the number of data.

Average = \(\frac{Total sum of data}{Number of data}\)

If x is used to represent the data and n is used to represent the number of data , then,

Source :passyworldofmathematics.com Fig :Mean
Source:passyworldofmathematics.com
Fig :Mean

Average = \(\frac{∑x}{n}\)

Here , the symbol '∑' means the summation of whole data.

Mean or average of ungrouped repeated data

Following are the steps given below to calculate the mean of ungrouped repeated data .

  • Draw a table with 3 columns and Write down the items (x) in the first column .
  • Write the corresponding frequency (f)of each item in the second column and find the produce of each item(x) and its frequency (f ) in the third (fx ) column.
  • Find the total of column andfx column and divide the sum offx by the sum off , the quotient is the required means .



  • The single number which represents the central value of a set of data is known as average .
  •  The data which is presented single or the graph which is drawn to present single type of data is called simple bar graph 
  • Mean is calculated by Average = \(\frac{∑x}{n}\) this formula.
.

Very Short Questions

Solution:

Let's present the above data of 16 workers in frequency table:

Wages () Tally
Marks
Frequency
60 ||| 3
70 |||| 4
80

|||| ||

7
90 || 2
Total   16

0%
  • The data which are presented properly are called ______ data .

    frequency
    arrayed
    bar
    raw
  • A ______ is drawn to show two or more related components of the given data.

    timeline
    bar graph
    multiple bar graph
    simple bar graph
  • A ______ is drawn to present a single type of data.

    timeline 
    bar graph
    multiple bar graph 
    simple bar graph
  • The systematical numerical figures are called ______ .

    bar 
    data
    frequency
    mean
  • A ______ is the number of times of a value occurs.

     mean
    bar graph 
    data
    frequency
  • You scored /5


    Take test again

ASK ANY QUESTION ON Statistics

No discussion on this note yet. Be first to comment on this note