CurriculumGrade 8Mathematics

Two-Way Tables & Relative Frequency

Aligned to 8.SP.A.4 — Common Core State Standards for Mathematics.

What this lesson teaches

A two-way table organizes categorical data in rows and columns. Relative frequencies — dividing a cell by a row, column, or grand total — reveal whether the two variables are associated.

Worked example

Of 50 students, 30 own a pet, and of those 24 enjoy the animals class. The relative frequency is 24 ÷ 30 = 0.8, so 80% of pet owners enjoy the class. Comparing this to non-owners shows whether owning a pet is associated with enjoying the class.

Practice questions

  1. A two-way table shows 40 students in total; 18 are in the "walks to school" row. Find that row's relative frequency of the total.
  2. Out of 25 girls, 15 play a sport. What is the relative frequency?
  3. Explain how comparing relative frequencies can show an association between two categories.

Watch the lesson

Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.

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En español

Tablas de Doble Entrada y Frecuencia Relativa

Una tabla de doble entrada organiza datos categóricos en filas y columnas. Las frecuencias relativas — dividir una celda entre un total de fila, columna o general — revelan si las dos variables están asociadas.

Ejemplo: De 50 estudiantes, 30 tienen mascota, y de esos 24 disfrutan la clase de animales. La frecuencia relativa es 24 ÷ 30 = 0.8, así que el 80% de quienes tienen mascota disfruta la clase. Comparar esto con quienes no tienen mascota muestra si tener mascota está asociado con disfrutar la clase.

More Statistics & Probability lessons

Scatter Plots & Association8.SP.A.1Fitting a Line to Data8.SP.A.2Interpreting Linear Models8.SP.A.3

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