# Problem Solving With Proportions

For instance if one package of cookie mix results in 20 cookies than that would be the same as to say that two packages will result in 40 cookies.$$\frac=\frac$$ A proportion is read as "x is to y as z is to w" $$\frac=\frac \: where\: y,w\neq 0$$ If one number in a proportion is unknown you can find that number by solving the proportion.

For instance if one package of cookie mix results in 20 cookies than that would be the same as to say that two packages will result in 40 cookies.$$\frac=\frac$$ A proportion is read as "x is to y as z is to w" $$\frac=\frac \: where\: y,w\neq 0$$ If one number in a proportion is unknown you can find that number by solving the proportion.

Tags: Custom DissertationsFamily Health Tree EssayCausal Argument Topics For A Research PaperFor An Arguementative EssayCreative Writing Year 3Transition Words For Essays To Start ParagraphBusiness Plan TempalteBusiness Plan PictureLearn Creative Writing Online FreeMajor Kinds Of Essay

The cross products of a proportion is always equal If we again use the example with the cookie mix used above $$\frac=\frac$$ $$\cdot =\cdot =40$$ It is said that in a proportion if $$\frac=\frac \: where\: y,w\neq 0$$ $$xw=yz$$ If you look at a map it always tells you in one of the corners that 1 inch of the map correspond to a much bigger distance in reality. We often use scaling in order to depict various objects. Thus any measurement we see in the model would be 1/4 of the real measurement.

Scaling involves recreating a model of the object and sharing its proportions, but where the size differs. If we wish to calculate the inverse, where we have a 20ft high wall and wish to reproduce it in the scale of 1:4, we simply calculate: $$20\cdot 1:4=20\cdot \frac=5$$ In a scale model of 1: X where X is a constant, all measurements become 1/X - of the real measurement.

We can also use cross products to find a missing term in a proportion. In a horror movie featuring a giant beetle, the beetle appeared to be 50 feet long.

However, a model was used for the beetle that was really only 20 inches long.

The following proportion is read as "twenty is to twenty-five as four is to five." In problems involving proportions, we can use cross products to test whether two ratios are equal and form a proportion.

To find the cross products of a proportion, we multiply the outer terms, called the extremes, and the middle terms, called the means.

If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.and *.are unblocked.

$$\frac=\frac\: \: or\: \: \frac=\frac$$ If we write the unknown number in the nominator then we can solve this as any other equation $$\frac=\frac$$ Multiply both sides with 100 $$\, \frac=\, \frac$$ $$x=\frac$$ $$x=10$$ If the unknown number is in the denominator we can use another method that involves the cross product.

The cross product is the product of the numerator of one of the ratios and the denominator of the second ratio.

## Comments Problem Solving With Proportions

• ###### Math Mammoth Ratios, Proportions & Problem Solving

Math Mammoth Ratios, Proportions & Problem Solving is a worktext that concentrates, first of all, on two important concepts ratios and proportions, and then on problem solving. The book is best suited for grade levels 6 and 7.…

• ###### Solving Proportions Worksheets -

Solving Proportions Worksheets Learn how to solve proportions with this set of worksheets that are specially designed for students of grades 6 and 7. A series of multi-level worksheets require students to solve proportions using the cross product method and the answers so derived will be in the form of whole numbers, fractions or decimals.…

• ###### Solving Proportions - Nearpod

Solving Proportions. Students will solve proportions using multiplication and division, including cross-multiplication, write proportions using a variable, and apply proportions as a problem solving tool. Math. Middle School.…

• ###### Solving Proportions - Grade 7 - Practice with Math Games

Earn up to 5 stars for each level The more questions you answer correctly, the more stars you'll unlock!…

• ###### Solving Proportions by Cross Multiplication.

An interactive math lesson about solving proportions by cross multiplication. Cross multiplication to solve proportions. A proportion is an equation which states that.…

• ###### Solving Proportions Examples - Shmoop

Solve the following proportion for x using multiplication. To get rid of those denominators, we multiply both sides of the equation by 515. The 5's cancel on the left, and the 15's cancel on the right.…

• ###### Proportions - Math Is Fun

Using Proportions to Solve Percents. A percent is actually a ratio! Saying "25%" is actually saying "25 per 100" 25% = 25100. We can use proportions to solve questions involving percents. The trick is to put what we know into this form PartWhole = Percent100…