MATH REVIEW: USEFUL MATH FOR EVERYONE
SECTION 1. RATIOS AND PROPORTIONS
- Ratios and Proportions
- Algebraic Expressions
- Exponents
- Logarithms
- Glossary and Links
A ratio compares two numbers in order. Ratios are written with a colon, like this:
4:3
The order of numbers in a ratio is important. The ratio 4:3 expresses a different relationship than the ratio 3:4 does.
The units of measurement that each of the two numbers expresses is important too. The two numbers in a ratio do not have to have the same units. One chicken to every pot (1 chicken:1 pot) is a ratio. Saying that one British Pound is worth about 1.5 US dollars (1 GBP:1.5 USD) is another ratio.
In some cases, it can be convenient to express ratios all in the same units, for example, the ratio of 9 cups to 16 cups may be written in two ways: with a colon 9:16 or as a common fraction 9/16. The fraction 9/16 is another way of saying 9 divided by 16.
The two numbers in a fraction are referred to so often that they have been given names. The top number in a fraction is the numerator and the bottom number is the denominator:
numerator / denominator
A fraction is another way of expressing one number divided by another. What is 24/56? You can take out a calculator and enter
24 / 56 = 0.42857
Incidentally, if you wanted to know what percent this fraction represented, simply multiply the number by 100, or move the decimal two places to the right.
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