Proportions

Robert Mattei
Class 702
Ms. Sa
April 03 - 2009

Aim: How do we solve proportions by using cross products?

Explain - The Term cross product helps me better because I just need to cross
multiply, the numbers. Also you can look at the ratio that is given in
your expression for an example. Use the ratio and make that the
denominator of the proportion and cross multiply.


6 4
----- , -----
12 6

This is an example of an proportion expression. Now, Cross Multiply !


Describe - 2 x
----- = ------- 2x = 36, x = 18
3 12

Its wrong its not suppose to be 36 it is suppose to be 24 not 36.
Then when you put 24 you will get the right answer.



Show - 6 2
------ ---------
45 15



6 • 15 = 90

2 • 45 = 90

The equation is Proportional because the answer is the same,
and if the answer is the same it is Proportional. But, if the answer
are not the same they are Non-Proportional.