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Measurement & Data - Statistics & Probability 229+

Unit 3: Lesson 1

Two-way frequency tables

Two-way frequency tables

Learn how to read and use two-way frequency tables.
Let's jump right in and look at a two-way frequency table that came from asking 100 students whether they prefer cats or dogs.
PreferenceMaleFemale
Prefers dogs3622
Prefers cats826
No preference26
The columns of the table tell us whether the student is a male or a female. The rows of the table tell us whether the student prefers dogs, cats, or doesn't have a preference.
Notice that there are two variables-- gender and preference-- this is where the two in two-way frequency table comes from.
The cells tell us the number (or frequency) of students. For example, the 36 is in the male column and the prefers dogs row. This tells us that there are 36 male students who prefer dogs.
How many female students prefer cats?

Row and column totals

To find the number of students that prefer cats, we just add up the number of students in the prefers cats row:
PreferenceMaleFemale
Prefers dogs3622
Prefers catsstart color #11accd, 8, end color #11accdstart color #11accd, 26, end color #11accd
No preference26
start text, S, t, u, d, e, n, t, s, space, w, h, o, space, p, r, e, f, e, r, space, c, a, t, s, end text, equals, start color #11accd, 8, end color #11accd, plus, start color #11accd, 26, end color #11accd, equals, 34
How many of the students are male?

Let's practice!

Problem 1

Researchers once surveyed college students on their Facebook use. The following two-way table displays data for the sample of students who responded to the survey.
How many students in the survey were in the age category of 18 to 22, question mark
students
18 to 22784
23, start text, plus, end text7067

Problem 2

Researchers once surveyed students on which superpower they would most like to have. The following two-way table displays data for the sample of students who responded to the survey.
How many males in the survey chose to fly as their superpower?
students
SuperpowerMaleFemale
Fly2612
Invisibility1432
Other108

Problem 3

Researchers surveyed recent graduates of two different universities about their income. The following two-way table displays data for the sample of graduates who responded to the survey.
How many graduates in the sample came from University A?
IncomeUniversity AUniversity B
Under dollar sign, 20, start text, comma, end text, 0003540
dollar sign, 20, start text, comma, end text, 000 to dollar sign, 39, start text, comma, end text, 9999063
dollar sign, 40, start text, comma, end text, 000 and over3537

Challenge problem

Lena knows the following information about her box of 18 candies:
• 10 candies contain both chocolate and caramel.
• 3 candies contain neither chocolate nor caramel.
• 12 candies in total contain chocolate.
Help Lena organize the results in the following two-way frequency table.
Contain caramelDo not contain caramel
Contain chocolate
Do not contain chocolate

Want to join the conversation?

• the question about help Elena organized in the following two way frequency table? How can you resolve it?
• First, the question tells us that Lena has 10 candies that have caramel AND chocolate so thus the first column and first row's value would be 10. Then we are told that there are 3 candies that do NOT contain chocolate OR caramel. This means that the value at column 2, row 2 would be 3. Then we are told that there are 12 candies that contain chocolate. So adding up both values in row 1 should be equal to 12 (10+X=12) which would give us 2 for Column 2, Row 1. We are also told that she has a total of 18 candies so adding up all values should give us 18 (10+2+3+X=18). Thus the value for Column 1, Row 2 would be 3. The complete answer would be:
C D
C 10 2
D 3 3
• I can do the ones with the numbers in the box but when the question doesn't have a box in it then I struggle with the question, how do you do the last question?
• First this is actually a analytic problem. You need to see the items,then to find the boxes that have the same information,and copy the number down.Sometimes it is hard to distinguish the information,you need to compare the items and the information in the boxes.
• How did Lena get 3 candies under the label of do not contain chocolate and also contains caramel? Please help me, I am having trouble understanding.
• We know that there are 18 candies in total, and 12 of them contain chocolate.
This means that 18 − 12 = 6 candies do not contain chocolate.

We also know that 3 candies contain neither chocolate nor caramel, and thereby there are 6 − 3 = 3 candies that don't contain chocolate but do contain caramel.
• whats the point of this bro
• Is relative frequency supposed to be written as a decimal or fraction?
• Relative frequency can be either a fraction or a decimal.

Have a blessed, wonderful day!
• how do I know that the 12 candies that contain chocolate don't contain caramel
• How did you find out there were 10 people that like chocolate but hates caramel
• The candies one was difficult and I'm sure I can speak for my class when I say this. I hope that our teacher doesn't end up putting a problem like this on our test. Yikes! That'll be scary/tuff if she do! Hahaha
• Honestly it was not that hard for me, rather a fun, quick, logic challenge.🙂