How to Determine If Numbers Are Proportional

You can determine if two numbers are proportional in a few key ways. Determine if numbers are proportional with help from a mathematician and educator in this free video clip.

Part of the Video Series: Algebra Help

Video Transcript

Hi my name is Marija and I'm a mathematician and today I'm going to tell you how to determine whether or not two numbers are proportional. So if we have the two fractions, 2/3rd and 4/6ths and we want to know whether or not this is a proportion. The easiest way to do it is to cross multiply and compare your products. So 6 x 2 is 12, write that number up here and 3 x 4 is 12. If the products, the cross products are the same, then you do have a proportion. Okay so these numbers are proportionate. If, let's do another one, let's say 3/7 and let's take 2/6. We want to know if these two ratios are proportionate. We're going to cross multiply. So 6 x 3 is 18 and 7 . 2 is 14. These two products are not the same, therefore these two fractions do not form a proportion and as a matter of fact, the fact that the 18 is larger than the 14, tells us that this fraction is larger than that fraction. So that's the easiest way to tell whether or not two numbers form a proportion.

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