1. Lesson 5-1: Using Proportions

2. Lesson 5-1: Using Proportions
Ratio
A ratio is a comparison of two numbers such as a : b.
Ratio:
When writing a ratio, always express it in simplest form.
Example: A B C D
3.6 6 8
4.8 10
Now try to reduce the fraction.
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Lesson 5-1: Using Proportions

3. Lesson 5-1: Using Proportions
Example……….
A baseball player goes to bat 348 times and gets 107 hits. What is the players batting average?
Solution:
Set up a ratio that compares the number of hits to the number of times he goes to bat.
Ratio:
Convert this fraction to a decimal rounded to three decimal places.
Decimal:
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The baseball player’s batting average is which means he is getting approxiamately one hit every three times at bat.
Lesson 5-1: Using Proportions

4. Lesson 5-1: Using Proportions
Proportion: An equation that states that two ratios are equal.
Terms
First Term
Third Term
Second Term
Fourth Term
To solve a proportion, cross multiply the proportion:
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Extremes: a and d
Means : b and c
Lesson 5-1: Using Proportions

5. Proportions- examples….
84 yards
2 ft x
356 yards
Find the value of x.
Example 2:
Solve the proportion.
8x = 30
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8 • x =
6 • 5
x = 3.75
8x = 30
Lesson 5-1: Using Proportions