Percents
4.1 Order of Operations
 
4.2 Numbers
 
4.3 Factors
 
4.4 Multiples
 
4.5 Fractions
 
4.6 Decimals
 
 
4.7 Percents
 
4.8 Exponents
 
4.9 Roots and Radicals
 
4.10 Logarithms
 
4.11 Review Questions
 
4.12 Explanations
 
Percents
A percent is another way to describe a part of a whole (which means that percents are also another way to talk about fractions or decimals). Percent literally means “of 100” in Latin, so when you attend school 25 percent of the time, that means you only go to school 25 /100 (or .25) of the time.
You would probably fail your classes if your attendance percentage were that low, so don’t get any ideas from our example. Instead, take a look at this question: 3 is what percent of 15? This question presents you with a whole, 15, and then asks you to determine how much of that whole 3 represents in percentage form. Since a percent is “of 100,” to solve the question, you have to set the fraction 3/ 15 equal to x/100:
You then cross-multiply and solve for x:
Converting Percents into Fractions or Decimals
You should be skilled at converting percents into fractions and decimals, because it will definitely come up on the Math IIC test.
Percents directly relate to decimal numbers. A percent is a decimal number with the decimal point moved two decimal places to the left.
For example:
To convert from a decimal number to a percent, move the decimal point two places to the right:
On an even simpler level, we can say, for example, that 50% = 0.5, or 22.346% = 0.22346. Percentages greater than 100 also exist. 235% = 2.35, for example.
To convert from a percent to a fraction, take the percentage number and place it as the numerator over the denominator 100. 58 percent is the same as 58 /100.
To convert from a fraction back to a percent, the easiest method is to convert the fraction into a decimal first and then change the resulting decimal into a percent.
For example:
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