Welcome to How to Find Quartiles (Odd Set of Data) with Mr. J! Need help with finding the lower quartile, median, and upper quartile? You're in the right place!
Whether you're just starting out, or need a quick refresher, this is the video for you if you're looking for help with quartiles. Mr. J will go through a quartiles example using an odd set of data and explain the steps of how to find the lower quartile, median, and upper quartile.
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Hopefully this video is what you're looking for when it comes to finding quartiles.
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welcome to math with mr j
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in this video i'm going to cover
quartiles so the lower quartile
the median and the upper quartile
quartiles divide data sets into quarters
simply put we break the data up into
four equal parts
the lower quartile will give us the 25th
percentile
so the 25 percent or one-fourth mark
the median gives us the 50th percentile
so the middle of our data and then the
upper quartile
will give us the 75th percentile the 75
percent or three-fourths mark
all of this information helps us
understand
and interpret data quartiles are a
building block for
other topics involving data so an
understanding of this
will help you moving forward in this
example
we're going to work with a data set with
an odd number of numbers
so let's jump into it and we need to
start by
ordering our data from least to greatest
so ascending order now in this example
the data is already in order but if
you're working with a data set that's
not
in order make sure least to greatest or
ascending order is the first thing you
do
the next step we need to find the median
also referred to as q2 which means
quartile 2 or the 50th percentile so
this is going to be
the middle of our data now for this
example
we have nine numbers in our data
set so the middle is going to be the
fifth number
that's going to give us four numbers on
the left and
four numbers on the right so the fifth
number
is this eight right here that's going to
be
our median so let's put
8 for quartile 2 or the 50th percentile
or the median now that's the middle
point
so what we need to do now we need to
find the median of the lower half
and the median of the upper half the
median
or middle of the lower half is going to
give us
the lower quartile and the median of the
upper half or middle of the upper half
is going to be the upper quartile so
let's take a look at the lower half
first
and we have four numbers here so we need
to find the middle
so we have an even number of numbers
within that
lower half we have four numbers so we
don't have a
specific number sitting directly in the
middle
so we're going to have to take a look at
the middle two numbers
the two and the four right here
now we need to find what's directly
in between that 2 and 4.
now we can think this through and we
know 3
is in between 2 and 4. but sometimes
it's not going to be that easy to figure
out so we need to do it mathematically
i'll show you how to do that as well and
we'll see if we still get 3.
so what we need to do if we need the
median
in between two numbers we find the
average
so we need to add then divide by two
so we have two plus four
and then divide by two that's going to
give us our
average so two plus four is
six and six divided by two
gives us three so we still got three so
three is our quartile one
or lower quartile
8 is our q2 to recap so our median
and now we need to end with finding our
upper quartile
so we'll take a look at the upper half
and we have four numbers here so an even
number of numbers so we need to take a
look
at the midpoint or middle
of our two middle numbers here so what's
going to be
in between 10 and 14.
so let's find the average between those
two numbers and that's going to give us
the median of that upper half so we do
10 plus 14
and we divide by 2 to find the average
so 10 plus 14 is 24
and 24 divided by 2 is going to give us
12. so 12 is going to be
our upper quartile so let's
split this data set into quarters or
four equal pieces to give you a visual
of
splitting this up so we know our 25th
percentile
or lower quartile is at 3 which is right
in between
2 and 4. so i'm going to draw a line
our median or 50th percentile
is this 8 right here so let's draw a
line
and then our upper quartile or 75th
percentile
is in between the 10 and 14
at 12. so you can see that we have
one two
three and four equal pieces
that's what quartiles are we split our
data set
into four equal pieces so there you have
it there's how you find
the lower quartile the median and the
upper quartile
i hope that helped thanks so much for
watching
until next time peace
