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Ratio and Proportion  Lesson 81
Today, we began to look at similarity. However, before we started, we had to review ratio, proportion, and a few relevant theorems:
The following theorems should be familiar to you...the first one is simply crossmultiplication and the second basically means that you can always exchange the means in a proportion and/or "flip" both sides of a proportion.
You should be very comfortable messing around with all these ratios and proportions. Remember to always leave your answers as fully reduced improper fractions...I really don't like (and will take points off for) mixed numbers and decimal approximations of improper fractions!!
We wrapped up the day by defining the arithmetic mean and the geometric mean of two numbers:
