An Introduction to Myself - Math Activity
Part II

Keeping the same ratio and proportion.

"Ratio" expresses in numbers the relationship between two things. It shows how big or small something is in relation to something else. For example, the female to male ratio at one of our colleges is 2 to 1 (2 males for every female).

The term "proportion" also refers to the relationship between to things. If something is in proportion, it maintains the same relationship to something else. For example, your tax increases in proportion to your income.

Right click the image below. From the choices you have listed, select PROPERTIES.


Under the PROPERTIES box, find the Dimensions of the image, expressed in PIXELS (Smallest units of an image).

1. Write the dimensions (width X height) in the box:    

If I want to keep the same proportions in the image when I make it smaller, I need to divide both the width and the height by the same amount. 

In other words, if I want to make the image half as small, I need to divide both the height and the width by 1/2, 50% or .50. If I don't the proportions will change, and the image may look like one of the pictures below:

If I divide both dimensions by the same amount, I will keep the same proportion, as shown below. 

2. Click on the image above and check the dimensions. 

Are the dimensions half of the original image? Did I keep the same proportions in the dimensions? Yes. 

Practice keeping the same proportions as you change the sizes in the following figures. Check the dimensions of the shapes below. 

3.     What would be the dimensions of a square twice as big?

4.   What would be the dimensions of a rectangle one-third of the size of this one ?


When we express rations, we often use a colon ":" to separate the two numbers. Six feet to two yards would be expressed as 6:2.

Example: 6 feet to 2 yards (6:2)  ( I multiplied or divided each side by the same amount and kept the same ratio)

5. 10:5       

6. 16:2   

7. 5:9       

We'll work more with ratios and proportions next time!

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ŠUnlimited Learning, 2004

Leecy Wise, author