Welcome to Understanding the Upper Quartile with Mr. J! Need help with upper quartiles? 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 an upper quartile example and explain the steps of how to find the upper quartile.
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Hopefully this video is what you're looking for when it comes to finding the upper quartile.
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welcome to math with mr j
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in this video i'm going to specifically
be covering the upper quartile
this is going to give us a better
understanding of what the upper quartile
is and represents it'll also give us a
better understanding of quartiles
overall now quartiles divide data sets
into quarters or four
equal parts the upper quartile is going
to be the
75 percent mark within our data
so the 75th percentile it separates the
upper 25 percent from the lower
75 percent so let's jump into our
example
to see exactly what this means and looks
like
so we have nine numbers within our data
set here
and the first thing we always want to do
is put the data in order
from least to greatest also known as
ascending order in this case we are
already in order so we can move to the
next step
we now need to find the median which is
the middle
of our data the 50th percentile
and since we have nine numbers within
our data set here
we're going to have four numbers on the
left and
four numbers on the right the number in
the middle
is our median and it's going to be this
8
right here so 4 numbers on the left
4 numbers on the right and our middle
number there 8
is our median to recap so median
equals eight
now once we have our median we need to
take a look
at the upper half of our data
so these four numbers
right here and we need to find the
median or middle
of that upper half that's going to be
our upper
quartile now since we have four numbers
in our upper half
we will not have one specific number
sitting in the middle
we will have to take a look at the
middle two numbers
and find what is in between and we'll do
that by finding the
average between them so our two middle
numbers
10 and 14. so we need to find the
average and that's going to give us the
middle or median
of that upper half so down here i'm
going to put
q 3 equals
so q3 means quartile 3.
that's the same thing as upper quartile
or 75th percentile all of those
mean the same thing so we need to find
the average and we can do that by adding
those two numbers together
and then dividing by 2. so 10
plus 14 and then
divide by 2. so 10 plus 14
gives us 24 and divide by
2 we get 12.
so our upper quartile is 12.
this means that 75 of our data
is less than 12 and 25
is greater than 12. so i'm going to make
some marks in our data to help us
visualize
and understand all of this and i'll
start with the median which again
was eight so this was our
median it's the midpoint of our data
the 50th percentile it splits our data
in half
now the upper quartile was between 10
and 14 at 12. so it
lies right here
and without going into detail our lower
quartile
is going to be between 2 and 4. i cover
that in another video i'll
add that link down in the description so
those
are our quartiles we split our data into
four equal parts
one two
three and four
so our focus was the upper quartile
which was right there
so to the left of that
we have 75 of
our data to the right of our
upper quartile we have 25
of our data so there you have it there's
an explanation
of the upper quartile i hope that helped
thanks so much for watching until next
time
peace
