Stem and Leaf Plots 03:18 minutes

Video Transcript

Transcript Stem and Leaf Plots

Buford the Bee Keeper competes in the annual Honey Production Competition. He wins the competition every year, so you'd think he’d be certain of a win this year too, but the bees've been buzzing with complaints about the working conditions, so he's not so sure.

The rules for the competition are pretty simple: each beekeeper enters 10 beehives and at least 3 of the hives must produce at least 30 pounds of honey annually. The data is presented in a stem-and-leaf plots.

Creating a stem-and-leaf plots

An advantage of stem-and-leaf plots is they are quick to make, and each data point is displayed. Let's have a look.
Using the numbers in this data set, first identify the smallest and largest numbers, or the minimum and maximum numbers, respectively. Then, create the stem, a vertical column listing the digits of each number excluding the rightmost digit. In this case, the whole parts of each number make up our stem. For the stem, don't list any repeats.

Next, create the leaves. In ascending order, list the digit in the ones place for each data point. For the leaves, repeating digits are allowed, so add a leaf for every data point. To double check that you listed all the data points, count the number of entries. There are 8 numbers in this data set, so there should be 8 leaves listed in the plot. A key is useful to help interpret the chart.

Example

Ok, now that we've reviewed how to make a stem-and-leaf plot, take a look at the data from Buford’s entry from last year. Here's a table with last years' honey production. He identified the smallest and largest data points, 18 and 41. The stem is the leftmost column and lists the digits of each number, but excluding the rightmost digit. So in this case, we write the tens digit of each data point, with no repeating digits. Therefore, our stem is made up of 1, 2, 3 and 4.

The numbers listed in column two are the leaves and represent the digits in the ones’ place for each number in the data set. Buford's stem-and-leaf plot looks good. He titled his plot: Pounds of Honey in Each Hive. Notice the leaves are listed in ascending order, and the repeats are listed as needed. The key shown at the bottom helps you understand the chart.

The data is easy to interpret. It’s obvious the most common values range from 30 to 39 and, to figure out how many beehives produced at least 30 pounds of honey – you can just count the leaves: one, two, three, four, five and six.

Back to Buford and his bees. Last years, he walked away with the prize but what about this year? He weighs the annual amount of honey for each beehive. The honey drips and so does Buford. He's really nervous.
Uh oh! What the buzz?! The honey production is way down! Buford wonders why the production of honey produced by the bees has decreased by so much, and he's determined to find out why. Oh no! The bees have gone on strike. Can you believe it? They want to form a union!