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and science in this video I'd like to go
over how to calculate your q1 your q3
and your IQR the interquartile range so
let me quickly go through the steps and
then I'll work an example
step one is order the numbers from least
to greatest step two will identify the
extremes step three will find the median
of the data set then step four we will
find the q3 or the upper quartile this
is the median of the upper half of the
data and you will only use the data to
the right of the original median for
this step and then step five will do the
same thing but for q1 and then we will
calculate the IQR or the interquartile
range by subtracting the lower quartile
q1 from the upper quartile q3 and here's
our list of numbers okay and so what I
did was I went ahead and put them in the
put them in order from least least to
greatest okay so step one is identify
the extremes so the extremes are 65 and
100 okay so I can write extremes 65 and
100 okay step three is I'm gonna find
the median of the data set and I'm gonna
do that by crossing numbers out so I'm
gonna cross these out
okay and now I am left with two so when
you are left with two whenever you have
an even number because if you count I
have one two three four five six seven
eight nine ten
you just take an average of the two
numbers and that will be 80 plus 82
which is 162
and then I'll divide that by two and
that equals 81 so the median equals 81
okay now step four is I'll find q3 or
the upper quartile okay so what I will
do is I will you need the same number in
each quartile so I have one two three
four five one two three four five so I
won't write the medium eighty one there
I'll just go with the numbers that you
have so this will be Q 3 and this set
will be Q 1 okay and so now to find the
median of this and I'm gonna rewrite
these numbers so it's not as messy I
have 82 85 90 95 and 100 okay so I'm
gonna cross them off like I did before
and the median is 90 so I will label
that Q 3 equals 9
now I'm gonna rewrite Q 1 I have 65 65
70 75 80
and seventy is your q1 okay and then for
my IQR I just take let me write this
here sorry I just take Q 3 and subtract
Q 1 and that equals 20 and that is your
IQR okay now let me point one thing
point one thing out if I had a an odd
number say 65 70 75 80 and 82 and I
needed to divide it into a q1 and q3 so
the median is 75 and so what I would do
it would not be included in q3 and it
would not be included in q1 okay because
you need the same number in each so
anyway I hope that helps with q1 q3 and
your IQR thanks for watching and
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