Big Ideas Math: Modeling Real Life, Grade 8
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Exercise 13 Page 266

The sums of the rows and columns in a two-way table are called marginal frequencies.

60 males and 70 females were surveyed. 104 students liked the recent school play and 26 did not. A total of 130 students were surveyed.

Practice makes perfect

A two-way table is a frequency table that displays data collected from one source that belongs to two different categories. One category of data is represented by rows and the other is represented by columns. We want to find and interpret the marginal frequencies.

Finding the Marginal Frequencies

We are told that boys and girls are surveyed about whether they liked a recent school play.

Student
Gender Liked Did Not Like
Male 48 12
Female 56 14
The sums of the rows and columns are called marginal frequencies. Let's calculate the sums of the rows.

Males:& 48 + 12 = 60 Females:& 56 + 14 = 70 Now, let's do the same for columns. Liked a Play:& 48 + 56 = 104 Did Not Like a Play:& 12 + 14 = 26 We can create new column and new row for the sums.

Student
Gender Liked Did Not Liked Total
Male 48 12 60
Female 56 14 70
Total 104 26

Finally, we have two ways of calculating the grand total. We can add the number of males to the number of females, or we can add the students who liked a play to the students who did not. These two numbers must be the same! Grand total l 60+ 70 = 130 104+ 26= 130 ✓ Finally, we can complete our table!

Student
Gender Liked Did Not Like Total
Male 48 12 60
Female 56 14 70
Total 104 26 130

Interpreting the Marginal Frequencies

In the marginal frequencies, we can see that 60 males and 70 females were surveyed. Moreover, 104 students liked the recent school play and 26 did not. A total of 130 students were surveyed.