Daily Scribe

3/31/10

In class, we did a review for the quiz tomorrow. We used this website called Quia, which has a bunch of games on it that help you practice math. We used it to practice finding percents using proportions, and things like that. An example of a problem we would do is 150 is what recent of 200. To find it, you can either use a scale factor or cross multiplying. You first set up the proportion, like

x/100=150/200. For this one, you could just use a scale factor. To get from 100 to 200, you multiply it by 2, so 150=2x. 150 divided by 2 is 75, so 150 is 75% of 200. A problem where you have to use cross multiplying is what percent of 130 is 45. You would set it up like x/100=7/13. To find out a problem like this, you multiply the denominator of the first number by the

700=x*13 numerator of the second(100*7). The product of that is also equal to the product of the variable x=53.85% and the denominator (x*13). So you divide the first product (700) by the denominator of the second number (13) to get the value of the variable(x).