How to Find Quartiles (Even Set of Data) | Math with Mr. J - Free Educational videos for Students in K-12

How to Find Quartiles (Even Set of Data) | Math with Mr. J - By Math with Mr. J

Transcript


00:0-1	Welcome to Math with mr J . In this video
00:05	I'm going to cover quartile so the lower quartile ,
00:09	the median and the upper quartile chortled , divide data
00:13	sets into quarters . Simply put we break the data
00:17	up into four equal parts . The lower quartile will
00:20	give us the 25th percentile so the 25% or 1/4
00:25	mark . The median gives us the 50th percentile ,
00:29	so the middle of our data and then the upper
00:33	quartile will give us the 75th percentile , The 75%
00:38	or 3/4 mark . All of this information helps us
00:42	understand and interpret data . Portals are a building block
00:47	for other topics involving data . So an understanding of
00:51	this will help you moving forward . In this example
00:54	we're going to work with a data set with an
00:57	even number of numbers . So let's jump into it
01:00	and we need to start by ordering our data from
01:04	least to greatest . So ascending order in this example
01:08	we are already in order . But if you're working
01:11	with some numbers that are out of order , make
01:13	sure you start with ordering those numbers from least to
01:18	greatest . So let's move on to step two which
01:21	is find the median . Now we have eight numbers
01:24	within this data set . So we're going to have
01:27	four on the left and four on the right ,
01:30	that's going to give us our middle , it's going
01:32	to be in between the 21 and the 28 .
01:37	So we need to find The middle between those two
01:41	numbers And we can do that by finding the average
01:44	. So let's come down to where it says Q2
01:46	which stands for quartile to which is the same thing
01:50	as the median , it's the 50th%ile . So to
01:53	find the average we need to add those numbers 21
01:58	plus 28 And then divide by two . So 21
02:03	plus 28 gives us 49 And 49 divided by two
02:10	, is going to give us 24 and 5/10 or
02:14	24.5 . That's going to be our median . That's
02:20	the middle point of our data set there . So
02:24	once we have our median we need to find the
02:27	median of the lower half and median of the upper
02:30	half . The median or middle of the lower half
02:33	is going to be the lower quartile and then the
02:36	median or middle of the upper half is going to
02:39	be the upper quartile . So let's do the lower
02:43	half first . So the lower four numbers , we
02:47	need to find the middle of those lower four numbers
02:50	. And since we have an even number of numbers
02:53	there , we don't have a number sitting directly in
02:56	the middle . So we're going to need to take
02:58	a look at the two numbers in the middle and
03:02	find what's in between . That's going to give us
03:06	our median again , because we don't have one specific
03:09	number sitting in the middle there , so we need
03:11	to take a look at the two in the middle
03:14	and find what's in between and just like the median
03:17	. We can do that by finding the average or
03:20	in the case of this one , we can probably
03:22	think it through and we know that 16.5 is in
03:25	between 16 and 17 . But let's solve it mathematically
03:30	as well . So again average add 16 Plus 17
03:36	and then divide by two . So 16 plus 17
03:41	is going to give us 33 divided by two and
03:45	we get 16 and 5/10 or 16.5 . That's going
03:51	to give us our lower quartile . So that's the
03:55	25% mark within our data set there , the 25th
04:00	percentile . So once we have that we can do
04:04	the upper quartile . So let's take a look at
04:07	the upper half and find the middle or median of
04:11	that upper half . Now we have four numbers again
04:14	an even number of numbers , so we're not going
04:17	to have one specific numbers sitting in the middle .
04:19	We're going to take a look at the two middle
04:22	numbers which 31 and 39 find the midpoint between those
04:28	two . That's going to give us our median of
04:31	that upper half and we can do that by finding
04:33	the average . So add 31 plus 39 divided by
04:41	two . 31-plus 39 is going to give us 70
04:48	70 divided by two , gives us 35 , so
04:53	35 is going to be the upper quartile , it's
04:57	the 75% mark within our data . The 75th%ile .
05:04	So those are our core titles . The lower quartile
05:07	is 16.5 , that's the 25th percentile . Then we
05:12	have the median , which is 24 a half ,
05:15	that's the 50th percentile , the middle of our data
05:19	set . And then for our Upper quartile we have
05:22	35 , so that's the 75th%ile . I'm going to
05:27	draw some lines within our data set there so we
05:29	can visualize where these chortled are and how it breaks
05:34	our data into four equal parts . So 16.5 is
05:38	going to be right here , Right in between that
05:42	16 and 17 that we talked about earlier , the
05:45	median , which is the middle point is right here
05:50	in between the 21 and 28 like we talked about
05:53	earlier and then we have our upper quartile In between
05:58	the 31 and the 39 . So you can see
06:01	that we have one , two , three and four
06:09	Equal pieces . This line right here represents the 25th%ile
06:15	. This line is the 50th and then this is
06:18	the 75th . So there you have it . There
06:21	is how you find the lower quartile , the median
06:24	and the upper quartile . I hope that helped .
06:28	Thanks so much for watching until next time . Peace
06:33	. Mhm .

Summarizer

DESCRIPTION:

OVERVIEW:

How to Find Quartiles (Even Set of Data) | Math with Mr. J is a free educational video by Math with Mr. J.

This page not only allows students and teachers view How to Find Quartiles (Even Set of Data) | Math with Mr. J videos but also find engaging Sample Questions, Apps, Pins, Worksheets, Books related to the following topics.