To determine if a problem situation is proportional or not put your information into a table.

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Proportional

The spreadsheet below shows a table that is an example of a propotional situation.

Notice that whenever you add a group of three boys, you must add a group of three girls. You can tell that this is proportional because you can set up equal ratios for each of the columns in your table.

or it may look like:

Explanations of how to determine if a situation is proportional.

If the table is proportional then each ratio (comparison) in our table should be equal. Suppose we compare the number of boys to girls
$\Large \frac{{boys}}{{girls}} = \frac{3}{5} = \frac{6}{10} = \frac{9}{15} = \frac{15}{25}\$


We know this is true because we can see that they are equal fractions, we can use cross products to verify this
$\[{}^{3\_ \bullet \_10\_ = \_30}\frac{3}{5} = \frac{6}{{10}}^{\_5\_ \bullet \_6\_ = \_30} \]$
Also,
$\[{}^{6\_ \bullet \_15\_ = \_90}\frac{6}{{10}} = \frac{9}{{15}}^{\_9\_ \bullet \_10\_ = \_90} \]$

And
$\[{}^{9\_ \bullet \_25\_ = \_225}\frac{9}{{15}} = \frac{{15}}{{25}}^{\_15\_ \bullet \_15\_ = \_225} \]$






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