L9 : Drawing Bar Graph - Data Handling, Mathematics, CBSE Class 6 Video Lecture

hello friends this video on data
handling part 9 is brought to you by
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now we will understand how do we draw a
bar graph and drawing enjoying a bar
graph
choosing the scale forms the most
important thing so let's say that we are
given this table there names of the
students and their marks are given so we
need to draw a bar graph so this is how
the bar graph would look like so here
also how do we so on the x axis it is
pretty simple because we have just
mentioned the names of the students and
on the y axis we have plotted the marks
so how did we decide the scale here now
normally we draw these graphs on a graph
paper so if you look at the graph paper
it
the papers are like it consists of
squares like this and even inside the
squares you have smaller squares like
this so basically from in one square so
if you look at its one side you would
have ten small squares so that is how
the bar graph paper is being made and we
make and we draw these bar graphs on
that graph paper okay so how do we
choose the scale in this case how did we
choose the y axis value now here for
that what we do is we first observe the
minimum value that we have in the
maximum value that we have so the
minimum marks that we have is 20 and the
maximum marks that we have is 15 so that
means the marks of all the students lies
between the range of 20 and 52 so
knowing this range will give you an idea
that how do you need to calibrate the y
axis the sense you saw that all the
numbers are between 20 and 50 - so you
thought that okay considering one box
has 10 units that is this one unit this
is one unit this is another unit this is
another unit and so on so here they have
considered one unit as ten marks that
means if this is zero this would be 10
so one unit represent
strike this is 10 this would be 20 so
this is one unit representing again 10
so if it is 20 this is 30 this is 40 and
so on so why did we choose this because
we need to go only up to 52 that means
we need to mark it only up to 60 because
52 would lie between 50 and 60 so 60
would mean just six squares so each of
these is one square so six square is
absolutely fine and it can be drawn on
the sheet of graph paper so that's how
we decided the scale on the y-axis but
sometimes the scenarios are a little
different so let us look at a scenario
like that so let's see this is how a
graph paper looks like so you see here
you have bigger squares like this and
then you have smaller squares inside
them so you the first step right for
drawing a graph bar graph is that you
draw a horizontal axis and a vertical
axis so we normally network this
horizontal axis as the x axis and the
vertical axis as the y axis and this
point where the x axis and the y axis
means it is quite the origin now you can
draw the bars both horizontally as well
as vertically that means that you can
have a bar graph like this like how you
have been seen in the last few slides or
you can also draw a graph like this so
these would be horizontal bars and these
are vertical bars so vertical bars are
most common more common but you can
choose any of these options but it is
just that if you were choosing this
option then definitely the marks need to
be along the wire
if around this axis the Mac's need to be
along the x axis and the names of the
students need to be along the y axis so
basically you have we will have to
interchange the two axis if you want to
draw horizontal bars but yes you are
free to draw either horizontally or
vertically that is up to you so now that
would be at the first step is to draw a
horizontal axis
and the vertical axis okay perfect so
the next step would be to look for the
range of numbers to be represented so
let us say let's take an example
so let's say that you want to represent
the marks hold by students with respect
to the students names now if you assume
that the students names would be along
the x axis and the marks scored will be
along the y axis so in that case let's
say it could be a pass here ramaa here
Sahin here so you will have streams of
students on this axis and then on this
axis you would have maybe the marks so
you will actually have graphs like this
so these are your vertical bars so why
are you drawing vertical bars because
you have kept the names of the students
on the y-axis but if you want to draw
horizontal bars in that case what you
will have to do you will have to keep
marks on the x-axis and names of the
students on the y-axis
okay so this part is clear considering X
and y axis
next part is choosing a scale so how do
we choose a scale so let us take this
example let's say this is this
represents the number of students in
different classes in class six seven
eight nine
they respectively have 20 45 60 and 70
students as I mentioned before that your
first job is always to draw the
horizontal and the vertical axis so
let's say this is your horizontal axis
and this is your vertical axis this is y
axis this is x axis and this is the
origin now in order to elects and let us
also assume that on the x axis we are
going to consider class and on the y
axis we are going to consider the number
of students now in number of students we
will have to look at the range so the
minimum number of student is 20 and the
maximum number is
seventy so that means the range of
values that you have is between 20 and
70 so what would be a convenient scale
so obviously a convenient scale would be
a scale of 10 that means we assume that
each unit represents 10 students so each
unit would mean each square like this so
this is one unit so this represents 10
students this is another unit which
would represent the largest end students
which would be 20 this would be 30 this
would be 40 50 60 and 70 so only in the
70 now we have taken only a small
section of the graph paper but when you
actually do it on a graph paper so there
it will be easy for you to mark from 0
to 70 you'll be able to do that very
conveniently on a sheet of paper so this
is how you choose the scale and once you
have chosen the scale then your job is
pretty simple you just need to draw the
bars for responding to 20 now again when
you draw the bars let you draw them
equally spaced that is they should be
spaced equally and their width should
also be the same let's say this is the
width that you are considering so this
would be your first bar and this bar
which represents 20 number of students
belongs to class 6
similarly for class 7 the number of
students are 45 so 45 would go even
beyond 40 so 45 would be somewhere
between 40 and 50 right now let's say we
have to represent a number between 10
and 20 so between 10 and 20 you again
have small boxes right so here 10 to 20
represents 10 students so that means
this is 10 this is 12 this is 14 this is
16 this is 18 this is 20 so basically
there are 5 equal divisions so those ten
students divided into five equal
division that means each division is for
two students so this represents 12
students this represents 14 16 18 and 20
so in that fashion you can kind of you
know accurately decide where 45 would be
so 45 would be exactly midway between 40
and 50 so maybe
they're here approximately and then this
bag that you get the presents class
seven
similarly class six would go even ten
16/9 would go even seventy so in this
fashion you will draw your bar graph
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