# Proportion

A ratio is simply a comparison between two quantities, obtained by dividing one quantity by the other. Example: The ratio of boys to girls in the class was 4:5

proportion is a name we give to a statement that two ratios are equal.

To be a proportion the cross products must be equal

Example:
To make 20 pancakes you have to use 2 eggs.
How many eggs are needed to make 80 pancakes?
20 X = 80 2
X=160/20
X=8

Unit Rates:

CM 1     Proportions (unit price)

A rate is a ratio that is used to compare different kinds of quantities.
Unit rate is a ratio between 2 measurements in which the second term is 1

### Finding the Missing Numerator

Two variables are proportional if a change in one is always accompanied by a change in the other.

Ratios in Proportional Relationships

The relationship between the diameter and circumference of a circle

### SF15       Similar_Cylinders

Measure the circumference and diameter of circular objects. Find the ratio of circumference to diameter for each object.

Ratio Relationship of π=C/d