Jim's Math Corner
by James W. Leonardi
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Middle School |
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Ratios & Proportions |
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RATIOS AND PROPORTIONS
RATIOS: The comparing of two items. Instead of comparing them side by side, we compare them by putting one over the other with a line in between --- a fraction. We have a numerator and a denominator. We may have a bigger numerator than a denominator --- an improper fraction. Most are written with the numerator smaller than the denominator --- a proper fraction. We may write a ratios as: 4/5 (a fraction) or 4:5 or 4 to 5. We do not do mathematics with the last two forms.
PROPORTIONS: Two ratios set equal. We may cross multiply proportions, and solve a problem algebraically. We will probably learn this in prealgebra. We can use proportions to put fractions (ratios) in ascending or descending order. Comparing two or more ratios (as proportions) are also a great problem solving technique. We may write proportions as: 4/5=16/20 or 4/5::16/20 or 4/5 to 16/20. We do not do mathematics with the last two forms.
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