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6 UNIT 1 Exploring One-Variable Data

We can use a frequency table or a relative frequency table to help describe the
distribution of a variable, as the following example illustrates.

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EXAMPLE call me, maybe? Skills 2.A, 2.B
Summarizing data with tables

PROBLEM: Here are the data on preferred method of communicating

with friends for all 50 students in the Census at School sample:
Internet chat/IM In person In person Internet chat/IM Phone call
Text messaging Text messaging Text messaging Social media Social media
Text messaging Text messaging Text messaging In person In person
Text messaging Text messaging Text messaging In person In person SDI Productions/E+/Getty Images
Text messaging Text messaging Internet chat/IM Social media Text messaging
Text messaging Text messaging In person Text messaging Internet chat/IM
Text messaging Social media Text messaging Social media Text messaging
Text messaging In person Social media In person Text messaging
Text messaging Text messaging Text messaging Internet chat/IM In person
Text messaging In person Internet chat/IM Text messaging In person

(a) Make a frequency table and a relative frequency table to summarize the distribution of preferred
communication method.

(b) Do these data support the claim that a majority of students prefer to communicate with their friends using text
messaging? Justify your answer.
SOLUTION:

(a) Frequency table
The frequency table shows the number of students who prefer
Preferred method Frequency each communication method. To create the frequency table, count
In person 12 how many students said “In person,” how many said “Internet chat
Internet chat/IM 6 or instant messenger,” and so on.
Phone call 1
Social media 6
Text messaging 25
Total 50

Relative frequency table
The relative frequency table shows the proportion or percentage
Preferred method Relative frequency of students who prefer each communication method. Note that in
In person 12/50 = 0.24 or 24% statistics, a proportion is a value between 0 and 1 that is equiva-

Internet chat/IM 6/50 = 0.12 or 12% lent to a percentage.

Phone call 1/50 = 0.02 or 2%
Social media 6/50 = 0.12 or 12%

Text messaging 25/50 = 0.50 or 50%
Total 50/50 = 1.00 or 100%

(b) No. Exactly 50% of the students in the sample said that they prefer to communicate with their friends
via text messaging, but a majority is more than half.
FoR PRAcTIce, TRY eXeRcISe 5

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