If you know the ratio of teachers to students in a classroom is 3 to 5, what else do you know?

If you know the ratio of teachers to students in a classroom is 3 to 5, what

else do you know?

In this lesson you will learn to identify implied information in part-to-part ratios by creating

and analyzing a diagram.

Let’s Review

A ratio is a comparison between two or more quantities that are related.

Part – to –Part

Part – to- Total

Rates

A Common Mistake

The ratio of teachers to students is 3 to 5.

For every three teachers there are five students.

That’s all we know!

Core Lesson

Your class recently voted for a class representative in your school’s student

government. The ratio of votes for Candidate A to Candidate B was 11 : 9.

Do I know anything else?

Core Lesson

Candidate A to Candidate B11 : 9

B B BB B BB B B

A A AA A AA A AA A

A has 11

B has 9

Total of 20 votes

920

1120

In this lesson you have learned to identify implied information

in part-to-part ratios by creating and analyzing a

diagram.

Guided Practice

The ratio of cats to dogs in a neighborhood is 3 : 8. How many total pets are there?

Extension Activities

For each scenario. Draw a diagram and fill in the sentence.

1. A ratio of cats to dogs is 2 to 7 implies total pets.

2. A ratio of 11 girls to 17 boys implies total students.

Extension Activities

The ratio of red to green to blue markers was 2 : 3 : 1. What part-to-total ratios do you know?

Quick Quiz

The ratio of cups of chocolate chips to butterscotch pieces in the recipe was 3 : 2. How many total cups of candy pieces were there?

The ratio of girls to boys in the classroom was 10 : 13. How many total students are there?