# If you know the ratio of students to teachers is 3 to 2 and you know there are 12 teachers, is there a way to figure out the number of students?

## Presentation on theme: "If you know the ratio of students to teachers is 3 to 2 and you know there are 12 teachers, is there a way to figure out the number of students?"— Presentation transcript:

If you know the ratio of students to teachers is 3 to 2 and you know there are 12 teachers, is there a way to figure out the number of students?

In this lesson you will learn to solve for missing values in a ratio problem by setting up a double number line.

Let’s Review A ratio can have equivalent ratios just like a fraction can have equivalent fractions. 2 : 1 x3 x3 6 : 3

A Common Mistake The ratio of students to teachers is 5 to 1. There are 15 teachers. 5 1 wrong line! students teachers 15 ?

Core Lesson Andy has a ratio of books to DVDS of 3 : 2 in his room. If he has 15 books, how many DVDs does he have? How can I use the ratio to help set up and solve?

Books to DVDs 3 to 2 15 books ? DVDS Books to DVDs 3 to 2 15 books ? DVDS Books 3 2 6 4 9 6 12 8 15 10 Andy has 15 books and 10 DVDs. +3 +2 DVDs +3 +2 +3 +2 +3 +2

Core Lesson +3 +3 +2 +2 x 5 x 5 multiplicative reasoning additive reasoning Books 3 23 2 6 46 4 9696 12 8 15 10 DVDs

In this lesson you have learned to solve for missing values in a ratio problem by setting up a double number line.

Guided Practice Anita collects shells and stones in a ratio of 2 : 1. If she has a total of 8 shells, how many stones does she have?

Extension Activities 1 15 3 10 5 students teachers 1 3 5 8 12 16 Fill in the missing values of the double number line. Write a paragraph explaining what ratio properties were used to create and fill in the lines.

Extension Activities Annie bakes cookies and cupcakes in a ratio of 4 to 3 for her gift boxes. Her school needs 35 desserts to sell in a bake sale. How many cupcakes will she bake? How many cookies will she bake? Create an illustration and a table to support your work.

Quick Quiz George buys oranges and apples at a ratio of 3 :4 for his party. If he has 15 oranges, how many apples does he have? Kelly bakes cupcakes and cookies in a ratio of 5 to 3 for her bakery. If on any given day she bakes 20 cupcakes, how many cookies did she bake that day?

Download ppt "If you know the ratio of students to teachers is 3 to 2 and you know there are 12 teachers, is there a way to figure out the number of students?"

Similar presentations