# Ratios and double number lines | Summary and Q&A

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November 8, 2017
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Ratios and double number lines

## TL;DR

Double number lines show the relationship between two variables and can be used to find ratios and values.

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### Q: What is the purpose of a double number line?

A double number line visually represents the relationship between two variables and allows us to determine ratios and values for different quantities.

### Q: How can we find the ratio between two variables using the double number line?

The ratio can be found by comparing the values on the number lines. For example, if the number line shows that 5 pounds of avocados cost \$9, the ratio is 5:9 pounds to dollars.

### Q: How can we calculate the cost of a specific quantity of avocados using the double number line?

To calculate the cost of one pound of avocados, divide the given ratio (in this case, 5:9) by 5. In the example, the cost of one pound of avocados is \$1.80.

### Q: How can we use the double number line to find the rate of building model trains?

By examining the number line, we can determine that the ratio of weeks to trains is 1:9. Thus, for every week, 9 trains can be built.

## Summary & Key Takeaways

• Double number lines illustrate the relationship between two variables, such as pounds of avocados and their cost, or minutes and number of snowballs made.

• By examining the double number line, we can determine ratios and values for different quantities of the variables.

• Ratios can be found by comparing the values on the number lines, and values can be calculated by multiplying or dividing the given ratios.