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How to Set Up Proportion Problems....5

There's a strong relationship between percents and proportions, as a percent can be written as a proportion. Solve percent or proportion problems whether or not the percent is given with help from a math teacher in this free video on proportions in math.

So, how does one solve percents and proportion problems? Hi, I'm Jimmy Chang, I've been teaching college mathematics for nine years, and there's actually a very strong relationship between percents and proportions, in that you can actually write a percent as a proportion itself. So, there's two kinds of problems involving this and let's do one of them right now. You have a situation where you want to find six is thirty percent of what number? Now, one thing to note here, is that percents are their own fraction and equation. Now, thirty percent can be written by itself as thirty over one hundred. Thirty percent out of a hundred percent. So like I said the percents get their own number. Now, on the other side, you have six is thirty percent of what number? Now, here's the clue that will always help you out. Whatever is after the word of is going to always be your denominator. Of what number? because we don't know, let's call that X, therefore, the six has to be on top. Now, basically after that, you cross multiply, the hundred is multiplied to the six, so you have six hundred and then X times thirty, the denominators multiply with the numerators on the other side. So, X times thirty is equal to thirty X. Solving for it, you divide both sides by thirty and then as a result you get X equals to twenty. Now, by the same token, if you want to find out percents then here's another scenario. What percent of ten is thirty? Now, because we don't know the percent, we have X over a hundred, because the maximum percent you should always have is a hundred. Now, of ten remember, the number after the of is ten, that means thirty is on top. You cross multiply, ten times X is ten X, one hundred times thirty is three thousand and then divide both sides by ten, you get X is equal to three hundred. So, you can solve percent or proportion problems either way, whether the percent is given to you or not. I'm Jimmy Chang and that has been solving percents and proportions in math.