NORTH HUNTERDON HIGH SCHOOL PRECALCULUS I TEACHER: MRS. PARZIALE
LESSON GUIDE – STEMPLOTS AND DOTPLOTS CHAPTER 1 – LESSON 2
Vocabulary: Stemplots are an organized way to analyze ________________ data. They can act as a _____________ of the ______________________ of the data. Stemplots are made up of __________ and ___________. The “leaf” is the last digit of a number. The “stem” is everything before the last digit. Minimum: ____________ value in a data set. Maximum: _____________ value in a data set. Range: __________________ of the maximum and the minimum. Outlier: A value in the data set that is ________ ________________ from any of the other values. Back-to-back Stemplots: Used to compare two related data sets. The ___________ is in the center column. The ____________ are on either side. Dotplots: represent numerical data and illustrate ____________________ Frequency: the number of times an item or event occurs Example 1: Consider the following grades on an Algebra II test on Matrices. 95 100 76
71 90 79
95 74 84
83 84 89
89 47 83
Construct a stemplot of the data.
a) b) c) d) e)
86 86
87 94
94 79
96 87
(Unordered)
92 76
84 75 (Ordered)
Grades on Matrix Test
Grades on Matrix Test
Stem
Stem
Leaves
Leaves
What is the minimum? What is the maximum? What is the range? Is there an outlier? What does 8|3 represent?
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NORTH HUNTERDON HIGH SCHOOL PRECALCULUS I TEACHER: MRS. PARZIALE
LESSON GUIDE – STEMPLOTS AND DOTPLOTS CHAPTER 1 – LESSON 2
Example 2: The Matrix test grades between Mrs. Parziale’s Mods 3-4 and 5-6 classes are shown below. Back-to-back Stemplots: Leaves (3-4) Stem Leaves (5-6) 4 7 75533 5 844 6 9955 7 1456699 7443 8 33444667799 9877773 9 0244556 0 0 10 0 a) identify the maximum and minimum scores for the mods 3-4 class. b) Is there an outlier for the mods 3-4 class? c) What is the range of both classes? d) How many students were in each class? e) How many students scored in the 80’s? f) What does 7|6| represent? g) What does |9|0 h) Does there appear to be a “gap” in one class? i) Are there any clusters of data?
Dotplots represent numerical data and illustrate frequency *best with small data sets with small ranges *easy to see clusters, gaps, and outliers How to make a Dotplot: 1. Draw a number line reflecting the necessary values 2. Record a dot for each occurrence of an event Example 3: Given the data below. Each value corresponds to the number of siblings a student has. Make a dotplot to represent the data. 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 5, 7
Example 4: The following data represents “Number of Hours Spent Exercising Per Week by Members of a Certain Health Club”. Make a dotplot to represent the data. 4, 6, 10, 7, 6, 11, 3, 6, 8, 7, 4, 6, 5, 6
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