Intro to Prob and Stats
CHS Stats
CHAPTER 2 REVIEW
SUMMARIZING AND GRAPHING DATA
MAIN IDEAS:
 Frequency Distributions, Relative Frequency Distributions, Cumulative Frequency Distributions
 Histograms
 Statistical Graphs (scatter plots, dot plots, stem plots, pie charts)
 Be able to understand and interpret results from frequency distributions and other graphs.
STATISTICAL LITERACY AND CRITICAL THINKING:
 Investigating distribution of a data set – a histogram is more effective than a frequency distribution
because a histogram provides a picture and a visual display is typically much easier to understand than
the table of numbers.
 Comparing two data sets – a relative frequency distribution is better than a frequency distribution
because relative frequencies use percentages rather than trying to compare data sets with significantly
different data values.
 Histogram features indicating normal distribution – the bars start relatively low, increase to some
maximum height, then decrease; symmetric with left half being roughly mirror image of the right half.
REVIEW EXERCISES:
1. The following sample data set lists the number of minutes 50 Internet subscribers spent on the
Internet during their most recent session. Construct a frequency distribution that has seven classes.
50 40 41 17 11 7 22 44 28 21 19 23 37 51 54 42 88 41 78 56 72 56
17 7 69 30 80 56 29 33 46 31 39 20 18 29 34 59 73 77 36 39 30 62
54 67 39 31 53 44
Time on Internet (min)
Time
Frequency (f)
7-18
19-30
31-42
43-54
55-66
67-78
79-90
Intro to Prob and Stats
CHS Stats
2. Using the frequency distribution in Exercise 1 find the midpoint, relative frequency, and cumulative
frequency for each class. Identify any patterns.
Class
7-18
19-30
31-42
43-54
55-66
67-78
79-90
Frequency Distribution for Internet Usage (in minutes)
Frequency, f
Midpoint
Relative Frequency
Cumulative Frequency
∑𝑓 =
∑
𝑓
=
𝑛
1
Interpretation:
3. Construct a frequency histogram for the frequency distribution in Exercise 1. Describe any patterns.
Interpretation:
4. How would the histogram change if you were to construct a relative frequency histogram?
5. What can a scatter plot tell you about the data points graphed?
Intro to Prob and Stats
CHS Stats