Writing some proportions

Got a question in today,
How can I solve the question, "write as many true proportions as you can with the numbers 3,6,9,12 and 18. Use a number only once".

This is a simple simple problem IF you know what the term "PROPORTION" means.

Proportion is simply an equation stating that one ratio is equal to another.

So to solve this, we play around and make ratios, and see if we can by happenstance come up with some equal ratios fitting the rule of using each number only once.

For example, 3:6 and 9:18 are two such ratios. So the PROPORTION then is (it needs an '=' sign)

3:6 = 9:18.

You can write the ratios using the fraction line, too.

Can you make others?

See also An idea of how to teach proportions.

Comments

Green Darner said…
When I read the question I wondered how we were to find the solution since there was an odd number of numerals. Then I realized that we weren't required to use ALL the numerals, just not to use them more than once in the solution.

So here are my solutions (for some reason I always think of proportions in fraction form - must be from working with sewing projects and all those 5/8's, 1/2's, and 1/4's lol):


9/18 = 6/12

3/9 = 6/18

6/9 = 12/18

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