Friday, April 3, 2009


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

In class I have been learning about proportions to find the answer we had to cross multiply. That way was better and not that confusing, Cross multiplying is easier for me because it makes tings more organized and easier for you to solve.

2 x
-- = ---
3 12 ; 2x = 36; x = 18.

There is a lot of things wrong with this. First of all the problem is disorganized. First she needs to cross multiply. 12 x 2= 24 so your problem should now look like this. 3x = 24 no you do inverse operation instead of multiplying you do the opposite divide. 24/3 equals 8 so x equals 8.

If you don't understand here is another problem for you.

6:45 and 2:15 are ratios but you can make them into fractions.

6 2
--- = ---
45 15

now we are going to find out weather this is proportional or not.

First you have to cross multiply. 15 x 6 =90
45 x 2 = 90 theses are equal, So yes these ratios are proportional.

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