IT IS A PPT ON THE MATHS CHAPTER DATA HANDLING..

2. INTRODUCTION
The main purpose of analysing data is to look
for a single value or values which describe the
main characteristics of the data.Such values are
called measure of central tendency.In this
chapter,we shall learn Mean,Median and Mode
as measures of central tendency and then
construct bar graphs.

3. WHAT IS DATA ?
Data is a collection numbers gathered to give
some information.For example,Sharad
secured 98% marks in the examination is a
data, whereas merely saying that he is very
intelligent is not a data.

4. ORGANISING DATA
The data and put without any specific
arrangement is called a raw data. For
example: Out of 20 mark, the marks obtained
by 10 students in mathematics are:
10,12,11,9,2,5,19,20,7,13

5. From this raw data, it is more time consuming
to answer even simple questions like:
(i) What is the maximum or minimum score ?
(ii) How many students got more than 17
marks ?
In order to simplify the process, we have to
organise data. For this, we arrange order as
below:
2,5,7,9,10,11,12,13,19,20
From this organised data we can answer above
given question easily.

6. RANGE
The range tells us how widely the numbers are
spread. In other words , range is the
difference of the highest and the lowest
observation.
Range = Highest Observation - Lowest
Observation

7. ARITHMETIC MEAN
In our daily life, we frequently use words, such as
average weights, average height, average price,
average marks, etc. Average is the number which
represents entire data.When we say that the
average weight of Class-VII students is around 45
Kg, this means that the weight of maximum
number of students is around 45 Kg. Only few of
them have a much lower weight and some have
much higher weight.

8. Thus, the knowledge of average weight gives us a
general impression of the weight of the students of the
class as whole
Averages are of different types. In this section, we
shall learn about a commonly known average
which is known as the arithmetic mean. It is
calculated by dividing the sum of all the
observation by the total number of observation, i.e
Sum of all observations
Mean =
Number of obsevation

9. EXAMPLE
QUESTION
The weight (in kg) of ten students of a class are:
43.5,49.5,52,43,47,44.5,38.5,40,47,38
(i) What is the mean weight ?
(ii) What is the range of the weights of the students
?
(iii) Find the number of students having weight
more than the mean weight.

10. SOLUTION
43.5+49.5+52+43+47+44.5+38.5+40+47+38
(i) Mean weight =
10
443.0
= kg = 44.3 kg
10

11. (ii) Arrange the data in ascending order, i.e
38,38.5,40,43,43.5,44.5,47,47,49.5,52
The greatest weight is 52 kg and the lowest weight
is 38 kg.
Therefore, the range of the given weights = (52-38)
= 14 kg
(iii)Number of students having weight more than
mean weight = 5

12. MEDIAN
The median is the value which is strictly in the
middle of the list of the observation when written
in ascending or descending order. It is also a
measure of central tendency.

13. MODE
Let us consider an example:
Read the bar graph given below showing the
number of students wearing shoes of different
sizes (in numbers).
0
100
200
300
400
500
shoe no
4
shoe no
5
shoe no
6
shoe no
7
shoe no
8
No. of students
No. of students

14. We can easily note that shoe of size number 7 is
worn by maximum number of students. The
manufacturer will manufacture the shoes
accordingly. The value which occurs the most is
called mode.
Mode is the observation which occurs maximum number
of times.

15. EXAMPLE
QUESTION
Find the mode of the following marks (out of
10)obtained by 15 students:
6,8,2,3,3,7,8,,5,8,8,1,8,9

16. SOLUTION
We arrange this data in the following form:
1,2,3,3,5,6,7,8,8,8,8,8,8,9,10
Here 8 occurs most frequently (6 times)
So , the mode is 8.

17. BAR GRAPH
Bar graphs can be drawn horizontally or vertically.
Here, we shall revise drawing of bar graphs for
given data by means of examples. We shall also
draw double bar graphs.

18. EXAMPLE
QUESTION
You are given a data showing the number of
students in different clubs of a school.Draw a bar
graph for the following data:
SCHOOL
CLUB
MUSIC
CLUB
DRAMA
CLUB
MATHS
CLUB
DRAWING
CLUB
LITERARY
CLUB
No. of
students
60 40 70 50 30

19. SOLUTION
0
10
20
30
40
50
60
70
80
MUSIC
CLUB
DRAMA
CLUB
MATHS
CLUB
DRAWING
CLUB
LITERARY
CLUB
No. of students
No. of students

20. DRAWING DOUBLE BAR GRAPHS
There are situations when we need to compare two
data. For that we draw double graphs. Let us
understand double bar graphs with the help of an
example.

21. EXAMPLE
QUESTION
Marks obtained by five students of class-VII in SA-
1 and SA-2 examinations, 2014 in mathematics
(out of 50) are given below. Represent this data by
means of double bar graph and answer the given
questions.

22. Students Swati Sharad Shekhar Arpit Sachin
Half-yearly
Exam
40 15 25 48 29
Final Exam 42 28 48 46 33
1.Do u see any improvement in SA-2 exams ?
2.Who has not done better than before in SA-2
exams ?

23. SOLUTION
On the horizontal axis, write the names of students
and on the vertical axis,write marks scored.Draw
bar graph side by side depicting marks obtained in
SA-1 and SA-2 examinations for each student.

24. 0
10
20
30
40
50
60
Swati Sharad Shekhar Arpit Sachin
SA-1
SA-2
STUDENTS
M
a
r
k
s
s
c
o
r
e
d

25. Ans 1 Yes, there is an improvement in the results in
all cases except one as the bars for SA-2
examination scores are higher in all except one.
Ans 2 Arpit has not done better in SA-2 exams since
in his case, SA-2 examination bar is lower than
the SA-1 examination bar.

26. THANK YOU
MADEBY – ROHANKUMARSAHU