Algebra Mrs. Hubbard

Ratios, Proportions & Percents Ratio- fraction Example: ½, Proportion- two or more equivalent fractions Example: ½ = 2/4 Percent- per every hundred Example: ½ = 50%

The most commonly used fractions… Benchmark Fractions The most commonly used fractions… Fraction Decimal Percent ½ 0.50 50% 1/3 0.333 33.3% ¼ 0.25 25% 1/5 0.20 20% 1/6 0.166 16.6% 1/8 0.125 12.5% 1/10 0.10 10% 2/3 0.66 66% ¾ 0.75 75%

Converting Fractions to Decimals Take the Top Number and Divide it by the Bottom Number. (you asked for it, now it’s back.) Mr. Duey video

Converting Decimals to Percents Move the Decimal Point two places to the Right. Example: Convert 0.50 to a Percent 0.50 = 50.0%

Converting Percents to Fractions Write the number in the Percent, as a number over 100, then Simply if necessary. Example: 50% = 50/100 = ½ Let’s Try It!

you have to do to the bottom what you do to the bottom, Proportions When Solving a Proportion problem, just remember…. What you do to the top, you have to do to the bottom OR what you do to the bottom, you have to do to the top. Let’s Try It!

Working With Percents Finding the Percent of a Number 10% Trick: To find 10% of any number, move the decimal point one place to the LEFT. This is a short cut for dividing by 10. Example: 10% of 20 = 2.0 10% of 25 = 2.5 10% of 888 = 88.8

Working With Percents If you can find 10% of a number, then you can easily find 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90%. It’s also easy to find 5%! Example: If 10% of 20 = 2 20% of 20 = 4 30% of 20 = 6 You Try It!

Working with Percents One percent Strategy Just like the 10 percent trick, we can use the One Percent Strategy to find 1% of any number. To Find 1% of any number, move the decimal point over two places to the left. (This is a short cut for dividing by 100) Example: 1% of 550= 5.50

Let’s Look at another Strategy We can solve Percent problems using a Proportion. Example: 80% of 30

Solving Proportions Answer: X = 24 80% of 30 = 24 Step 1: Cross Multiply. 80 x 30 = 100X Step 2: Multiply 2400 = 100X Step 3: Solve 2400 = 100 x 24 Answer: X = 24 80% of 30 = 24

Keep up the Great work!