# What is ratio?

##### Intros
###### Lessons
1. Introduction to What Is Ratio
##### Examples
###### Lessons
1. Understanding Ratio Tables

Fill in the blanks in the following ratio table.

 x y 4 8 14 21
1. Part-to-part Ratio Vs. Part-to-whole Ratio

There are 14 boys and 16 girls in a particular class.

1. Find the ratio of boys to girls.
2. Find the ratio of boys to the whole class.
2. Charlie bought 2 Superman action figures and they are 4.4 cm and 9 cm tall respectively. What is the ratio of the height of the smaller figure to the larger figure?
1. Evaluate Ratios Involving Unit Conversion

Betty and Mary participated in a 400 m sprint. Betty finished it in 1 min 40 sec while Mary finished it in 2 min 15 sec. What is the ratio of Mary's time to Betty's time?

1. Determine the Scale of a Map (Ratio)

The distance between two cities on a map is 4 cm. If the real distance between the cities is 28 km, what is the scale of the map?

1. A Tyrannosaurus (a dinosaur) is 12.3 m in length. If a model was built using the ratio 1:15, what is the length of the model?
1. Analyze Ratios of 3 Objects

A bank wants to maintain the managers, analysts and tellers in the ratio 2:5:18. If 15 analysts were hired, how many managers and tellers should they hire?

###### Topic Notes
In this lesson, we will learn:
• Understanding Ratio Tables
• Part-to-part Ratio Vs. Part-to-whole Ratio
• Evaluate Ratios Involving Unit Conversion
• Determine the Scale of a Map (Ratio)
• Analyze Ratios of 3 Objects

Notes:
• A ratio shows the relative values of two or more objects
• A punctuation mark colon (:) or the word "to" is used to separate the values.
• A ratio can be expressed as a fraction, which can be further converted to a decimal or a percentage.
• A ratio should always be in its simplest form (no common factors).
• The values in a ratio should always be integers if possible.
• A ratio can be scaled up/down by multiplying/dividing the ratio numbers by the same value. This process is called scaling, and the value used for scaling is called the scale factor.
• There are two types of ratio:
• Part-to-part (comparing one part to another)
• Part-to-whole (comparing one part to the whole)