What a Ratio Means
Aligned to 6.RP.A.1 — Common Core State Standards for Mathematics.
What this lesson teaches
A ratio compares two amounts and tells you how they go together. You can say it as 'a to b', write it as a:b, or as the fraction a/b — they all mean the same relationship.
Worked examples
Example 1
In a bag with 4 red marbles and 6 blue marbles, the ratio of red to blue is 4:6. For every 4 red, there are 6 blue. Written as a fraction that is 4/6.
Example 2
A class has 10 boys and 15 girls. The ratio of boys to girls is 10:15, which simplifies to 2:3.
Example 3
Watch what is being compared. Boys to girls is 2:3, but boys to the whole class is 2:5 — a part-to-part ratio is not a part-to-whole ratio.
Practice questions
- A class has 10 boys and 12 girls. Write the ratio of boys to girls three ways.
- A recipe uses 2 cups of flour for every 1 cup of sugar. Describe this relationship in ratio language.
- In a parking lot there are 15 cars and 5 trucks. Write the ratio of trucks to total vehicles.
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.
▶ Watch this lessonEn español
Qué Significa una Razón
Una razón compara dos cantidades y muestra cómo se relacionan. Puedes decirla como 'a a b', escribirla como a:b, o como la fracción a/b: todas expresan la misma relación.
Ejemplo 1: En una bolsa con 4 canicas rojas y 6 azules, la razón de rojas a azules es 4:6. Por cada 4 rojas hay 6 azules. Como fracción es 4/6.
Ejemplo 2: Un salón tiene 10 niños y 15 niñas. La razón de niños a niñas es 10:15, que se simplifica a 2:3.
Ejemplo 3: Fíjate qué se está comparando. Niños a niñas es 2:3, pero niños al salón entero es 2:5 — una razón parte-a-parte no es lo mismo que parte-a-todo.
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