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Hello my name is Beth Dixon and this is a video series based on Vicki Borlaug's PowerPoint presentation on the mean median mode
and midrange the measures a center I wish thank Mrs. Borlaug for allowing me to use her PowerPoint to create these videos
this is the second video in the series and we will start with the median
I am using the same data that I used in the first video where I found the mean
now I want to look at the median
this will be the middle number
since it is the middle number
there must be order mathematicians are a little OCD if everyone could use and list their data in a different order
then everyone would get a different middle number
so the first step is to put the data in ascending order
ascending means counting up from the smallest to the largest
our data is already in order remember that the median is now
the middle number
we can have two cases
the sample size or population size
being odd or even
if the sample size n is odd
the median will be at data value
if the sample size is even
the median and will be halfway between the two data values
here is our data again
how many values do we have
we have 20
that is an even number
watch what happens
counting from both the ends
what is the middle number
there is no single middle number or number in the middle there are 10 and data values on each side
the median will be the number
in between the left and right hand side of the list
at the middle where we are looking for the middle or the median we have a four and a five and the median is between them
the median then is halfway between the data values of four and five
to find the median when we have an even number add the two numbers in our case for plus five
and then divide by two
that gives us 4.5
remember you order of operations
four plus five have to be added before we divide by two and do that carefully on your calculator
let's do a quick review of what we have found
find the middle number or numbers
that the data in ascending order
the median is the middle number
since we had an even sample size we'll add
four plus five to get nine
then divide by two which gives us 4.5
notice where that falls on the picture of our data
approximately 50% of the numbers fall below this and 50%
are above this number
notice in this example there is exactly 50% to the left and 50% to the right of the median
we can count
10 blocks
to the left and 10 blocks to the right just as we counted 10 blocks and 10 data to the left into the right on each side of the median
to keep the videos short and so that you're not having to listen to any one for very long and
going to end this video here and we'll pick up the next one on the mode and midrange thank you for watching
All spelling errors are mine--no comments or laughter please. Beth Dixon