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# Stem-and-leaf plots

AP.STATS:
UNC‑1 (EU)
,
UNC‑1.G (LO)
,
UNC‑1.G.2 (EK)

## Video transcript

a statistician for a basketball team tracked the number of points that each of the 12 players on the team had in one game and then made a stem and the leaf plot to show the data and sometimes it's called a stem plot how many points did this team score and when you first look at this plot right over here it seems a little hard to understand understand you have 0 1 2 under leaf you have all of these digits here how does this relate to the number of points each student or each player actually scored and the way to interpret a stem and leaf plot is the Leafs contain at least the way that this statistician used it the leaf contains the the smallest digit or the ones digit in the number of points that each player scored and the stem contains the tens digits and usually the leaf will contain the the rightmost digit or the ones digits and then the stem will contain all of the other digits and what's useful about this is it gives kind of a distribution of where the players were you see that most of the players scored points that started with a zero then a few more scored points that started with a 1 and then only one score scored points that started with a 2 and it is actually 20 points so I'm going to actually write down all of this data in a way that maybe you're a little bit more used to understanding it so I'm going to write the zeroes in purple so there's let's see 1 2 3 4 5 6 7 players had to 0 as the first digit so 1 2 3 4 5 6 7 I wrote seven zeroes and then this player also had a zero in his ones digit this player I'm going to try to all the colors this player also had a zero in his ones digit this player right here had a two in his ones digit so he scored a total of two points this player let me do orange this player had four for his ones digit this player had seven for his ones digit then this player had seven for his ones digit and then let me see I'm almost using all the colors this player had nine for his ones digit so the way to read this is you had one player with zero points zero to four seven and nine but you can see I'm it's kind of silly saying that zero was the tens digit you could have even put a blank there but the zero lets us know that they didn't score they didn't score anything in the tens place but these are the actual scores for those seven players now let's go to the next row in the stem-and-leaf plot so over here all of the digits start with or all of the point start with one for each of the players and there's four of them so one one one and one and then we have this player over here it's one his ones digit or her ones digit is a one so this player this represents eleven one in the tens place one in the ones place this player over here also got eleven one in the tens place one in the ones place this player let me do orange this player has three in the ones place so he or she scored 13 points one in the tens place one three in the ones place thirteen points and then I will do this in purple this player has eight in the ones place so he or she scored 18 points one in the tens place eight in the ones place eighteen points and then finally you have this player that has two the the tens digit is a two and then the ones digit is a zero is a zero I'll circle that in yellow it is a zero so he or she scored 20 points so using the using looking at the stem-and-leaf plot we were able to extract out all of the number of points that all of the players scored and once again what was useful about this is you see how many players scored between 0 and 9 points including 9 points how many scored between 10 and 19 points and then how many scored 20 points or over and you see the distribution right over here but let's actually answer the question that they're asking us to answer how many points did the team score so here we just have to add up all of these numbers right over here so we're going to add up I'll start with the largest so 20 plus 18 plus 13 plus 11 plus 11 13 11 11 plus 9 plus seven plus seven again plus four plus two did I do that right we have two 11s then a nine then two 7s then a four then a two and then these two characters didn't score anything so let's add up all of these together let's add them all up so 0 plus 8 is 8 plus 3 is 11 plus 1 is 12 plus 1 is 13 plus 9 is 22 plus 7 is 27 34 38 30 or 40 so that gets us to 40 let me do that one more time 8 11 11 12 13 22 29 29 and then 20 minutes 29:36 40 and 42 looks like I actually might have missed let me do it one more time this is the hardest part adding these up let me try that one last time I'm just going to state where my sum is so 0 8 at 3 11 12 13 20 to 29 36 40 42 so it's good thing that I double-check that I had made a mistake the first time 4 plus 2 is 6 7 8 9 10 so we get to 102 points the team in total scored 102 points
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