Constructing a stem-and-leaf plot
Howdy! I'm Professor Curtis of Aspire Mountain Academy here with more statistics homework help. Today we're going to learn how to construct a stem-and-leaf plot. Here's our problem statement: Construct a stem-and-leaf plot of the test scores 68, 73, 85, 75, 89, 89, 87, 90, 98, and 100. How does the stem-and-leaf plot show the distribution of these data?
OK, we could go old school and construct the stem-and-leaf plot from our data set by hand, but I'm gonna use technology because I'm living in the 21st century where we have this wonderful technology that can do a lot of the heavy lifting for us. So that's what I'm gonna do.
So here in StatCrunch I have the actual data set that I'm given here in the problem statement. And now that I've put this in, I'm ready to construct my stem-and-leaf plot. To do that, I go up to Graph –> Stem and Leaf. In the options window, I'm gonna select the column where my data is located and then hit Compute! and here's my stem-and-leaf plot already made for me.
Now all I need to do is figure out which of these answer options matches the stem-and-leaf plot given to me in StatCrunch. And that's going to be — looks like this one. I check my answer. Nice work!
And now the second part of our problem asks, “How does the stem-and-leaf plot show the distribution of this data?” Well, if you look at the way this is formatted it looks kind of like a histogram on its side. And that's essentially what we're looking at, where the stems correspond to the categories or classes of a histogram and these leaves here correspond to the heights of the bars.
So the more numbers you have within a given category or class, then that means you've got a greater frequency count for that category. That's really what we're looking at here. So what are our answer options? The lengths of rows are gonna be similar to the heights of the bars in a histogram because this is on its side. So we're looking at answer options C or D. And then longer rows of data correspond to higher frequencies. I check my answer. Excellent!
And that's how we do it at Aspire Mountain Academy. Be sure to leave your comments below and let us know how good a job we did or how we can improve. And if your stats teacher is boring or just doesn't want to help you learn stats, go to aspiremountainacademy.com, where you can learn more about accessing our lecture videos or provide feedback on what you'd like to see. Thanks for watching! We'll see you in the next video.
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