|
|
|
|
|
|
|
||
|
|
|
|
|
Proportions: Introduction (page 2 of 6) Sections: Ratios, Proportions, Checking proportionality, Solving proportions A ratio is one thing compared to or related to another thing; it is just a statement or expression. A proportion is two ratios that are equal to each other; a proportion is an equation that can be solved. When I say that a proportion is two ratios that are equal to each other, I mean this in the sense of two fractions being equal to each other. For instance, 5/10 equals 1/2. Solving a proportion means that you are missing one part of one of the fractions, and you need to solve for it. For instance, suppose you were given: x/10 = 1/2 You already know that x must be 5, but suppose you didn't notice this. You can then solve the equation x/10 = 1/2 Multiply through by 10 to clear the denominators: 10( x/10 ) = 10( 1/2 ) x = 5 Copyright © Elizabeth Stapel 2006-2008 All Rights Reserved ...to get that x = 5, so 5/10 = 1/2. Of course, proportions wouldn't be of much use if you only used them for reducing fractions. A more typical use would be something like the following:
.(ducks)/(geese) : 16/9 = 192/G I'll multiply the G up to the left-hand side, and then solve for the value of G: .16/9
= 192/G
Then there are 108 geese. Notice how I wrote out the ratio in words: (ducks)/(geese) This is not standard notation, but it can be very useful for setting up your proportion, because it will help you keep track of what each number stands for. In other words, it will help you set up your proportion correctly. If you do not set up the ratios consistently, you will get an incorrect answer, so clarity can be very important. << Previous Top | 1 | 2 | 3 | 4 | 5 | 6 | Return to Index Next >>
|
|
|
|
Copyright © 2006-2008 Elizabeth Stapel | About | Terms of Use |
|
|
|
|
|
|
