Lines Graphs in Data Interpretation Video Lecture | Study Integrated Reasoning for GMAT - GMAT | Best Video for GMAT

hello and welcome to a session of data
interpretation in this session we shall
look at examples of line graphs let's
have a look at the graph now in this
graph okay let's look at the directions
consider the following graph and answer
the question based on it so there is
nothing much in the directions but we
have to read the graph carefully now on
the x-axis it is 0 2 4 8 6 which is the
months and on the y-axis it is
calories let's look at the bottom
calories required per day by baby boys
and baby girls in the first 18 months of
their lives
so this graphs gives us what the calorie
requirement of babies of say 2 0 2 4 6 8
corresponding to 18 months for boys and
girls separately boys the lines is given
in terms of triangles and the girls it
is given in terms of circles so here in
the same graph we have boys girls two
lines what all do we understand by these
lines now if a line now if I see two
things first of all the corresponding
points now the difference between each
and every corresponding point is same
which is two months zero 2 4 6 8 10 12
14 16 18 so it's all but it's actually
constant so there's only two months so
if a line is steeper or rather it's at a
higher elevation then it shows us what
it's a higher incline or higher
increment or a higher increase if it is
slightly flatter which means it's a
lower increase if the line is actually
going down from one point to the next
corresponding point then there is a
decrease so by looking at just the line
the the angle at which it is inclined or
it is declined we can outrightly say
that yes there is an increase at a high
increase or a low increase compared to
another one or a decrease let's start
looking at the questions now at what
ages are the requirements of calories
for baby boys and baby
it's equal we can also look at
calculating each one of them but then
how do we see it now the points at which
both of them are intersecting with each
other or overlapping is the point at
which they are equal now if I start zero
months okay they are not overlapping at
two months since they're overlapping so
boys and girls are at the same point if
I go further 4 no 6 no 8 yes again at 8
they are overlapping if I go ahead 10 no
12 14 16 18 none of them are overlapping
so I can very clearly say at 2 months
and at 8 months they are overlapping
which means that their calorie
requirement happens to be the same at
these two points which is two months in
8 months
hence the last option which gives us two
months and eight months is the right
option let's have a look at the next
question in the same graph the
difference between the calories
requirements for baby boys and baby
girls at the age of six months is
approximately equal to if you look
closely into the graph there is a there
are lines between 0 and 500 how many
lines are there let's start counting one
two three four lines so I can very
clearly say that the first line is
corresponding 200 second is 200 third is
300 fourth is 400 same way for the
entire vertical axis same thing is
replicating so from thousand to fifty
hundred is 1,100 1,200 1,300 1,400 now
let's start finding for girls at six
months the circle is where slightly
below 1500 as the line just below 1500
so it is 1,400 for boys it is two lines
above 1500 so it is what 1600 and 1700
so there is 1,400 for girls 1700 for
boys so the difference is what 300
calories so 300 is actually the right
option which is option A let's look at
the next question if in a family there
are for baby boys aged 4 6 8 and 12
months respectively and 3 baby girls
aged 2
eight and sixteen months respectively
then what is the total calories required
to many boys and girls in same family
but let's start looking at it at the age
of four months now four months it is one
notch below 1500 the triangle is one
much below 1500 let's complete the boys
first so for six months six months it is
two notches above 1500 so it becomes
1700 for eight months it is bang-on 1500
so that's 1500 for 12 months okay 12
months it is actually if you look it is
at 3,000 so 3,000 so it's 1,400 plus
1700 plus 15 hundred plus 3,000 that is
the requirement for boys what about
girls so two months at girls is two
notches above thousand so the circle
which is actually overlapping so it's
1200 then for the eight months eight
months it is exactly on 1,500 and for 16
months it is exactly on 2,000 so 1500
plus 2,000 plus 1200 so the total for
every one becomes twelve thousand three
hundred which is the first option so
twelve thousand three hundred is the
right option let's have a look at the
next question
it can be inferred from the graph that
in general calorie requirements for baby
boys and baby girls now there are four
things given completely on different
things so we'll have to check each one
of them so let's see for the first one
the calorie requirement for baby boy and
baby girls are quite different at all
ages at all ages it is not at almost all
ages so at all ages means they have to
be different at all but the first
question said if you remember it was two
months in eight months where we found
out that both of them are same so they
are technically not same at all ages at
two not different at all ages at two
months and eight months they are same so
first statement actually is not
completely true or rather I cannot mark
it true let us look at the second
statement
calorie requirements for baby boys and
maybe girls are similar till the age of
70 months this again is not same because
they are not similar at one point in
time this is going on up and another
point there is going down so if you look
at from zero to two months both of them
go up to two for one of them goes up one
of them goes down so there is no
similarity there right so we cannot
again mark the second option correct
let's forget it third statement reaches
a peak value at the same age wait a
second
when is the peak value for the boys
looking at the triangles it's 16 months
when is the peak value for girls it is
14 months so this also is not true hence
the last option which is none of these
happens to be true because the first
three options are not actually getting
you somewhere let's have a look at
another type of example let's have a
look at this figure the following graph
gives us information about the number of
washing machines produced by hll during
1992 2004 okay now this is again a line
graph but here there are two separate
y-axis one on the left and one on the
right one on the left gives us number of
machines and thousands and one on the
right gives us total value of machines
in rupees crores and the figure shows
washing machines manufactured by a
chelate the one which is the gray box
gives us the number of machines now
number of machines has to be compared
with the left side which is left axis
whereas one on the right gives us the
value of machines which is in
transparent triangles let's look at the
question now what was the value of each
machine in the year 2000 now in the year
2000 let's have a look at both the
values number of machines and value of
machines because total value of machines
divided by total number of machines will
give me value of each machine right so
number of machines for number of
machines I have to go for the gray
blocks and then I have to refer to the
left axis which is number of machines
axis so here it is slightly above 4 so I
and probably assumed it to be around
4500 and what about the right hand side
now that gives us the total value of
machines for the total value of machines
if I start assuming it will be somewhere
around 25 or rather 25 crores 25 crores
divided by 4,500 will give me how much
will give me the second option which is
fifty five thousand five fifty five that
will be the right option here so this is
how in the same graph there are two
separate accesses or other two separate
reference columns for each line or each
point here there is only one question
but suppose they were toward three or
four more questions then it is always
wise to start putting the values which
are required looking at the question had
it been the value of two thousand also
required in 2001 and 2002 I would have
preferred to write down the three
corresponding values of these ones right
at the outset because the confusion can
be very easily created by the two axis
anyways using the line graphs we can
actually find out a lot of things the
slope of the line will give us an idea
about the increase or the decrease so we
will have to keep that in mind
while solving and of course use mental
calculations to make the calculations
easier and faster all the best