Ratios+&+Proportions

If there are 5 erasers and 3 pencils the ratio of erasers to pencils can be written as: 5 to 3, 5 : 3, or 5/3. there's 10 boys and 12 girls. the ratio to boys to girls is 10:12
 * Ratios** - a comparison of two numbers. It can be written 3 ways

gcf(greatest common factor) GCF of 20 and 28 is 4 (20: 1, 2, __4__, 5, 10, 20) (28: 1, 2, __4__, 7, 14, 28) 1. List all factors of both numbers 2. Find the largest factor that BOTH numbers have 3. Divide both numbers by the factor or GCF

Equivalent ratios: two or more ratios that have been converted untill they are equal. Rate: a rate is a comparison of two numbers with different units of measure. Unlike proportions, they don't have to equal. Unit rate: when there is a comparison of two quantities, but there's only one unit. Simplify ratios to get a unit rate. **Proportions** - two equal ratios Ex. If it costs $2 for 6 pizza slices and you want 12 slices, how much will it cost? To solve proportions use cross multiply 1. Find cross products(2×12) 2. Multiply the two factors(2×12=24) 3. What number will work on the other sidethat's equal to the first?(6×?=24) If you cross multiply, you will find that it costs $4 for 12 slices = = Pizza [Online Image] [] 5/8/09

similar figures: shapes that are the same but not the same size are similar

**Easy Problems:**
What's the **GCF of 9 and 6?** **9-1,3,9 6-1,2,3,6** Answer: the GCF is 3

There are 12 boys in the class and 14 girls. what is the ratio of boys to girls Answer: 12:14

Is **200 heartbeats/2minutes** equal to **500 beats/5 minutes**? Find the **unit rate** to answer! Answer: Yes. The unit rate is 50 beats/.5 minutes

** Medium problems: **
What's the GCF of 16 and 64? Answer: 16

Write a ratio equal to 2 to 5.

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For more help on ratios, go to: [] []

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