1. 2-6 Ratios and Proportions
Ratio: A comparison of 2 numbers by division. Either using a colon or, more commonly in this chapter, as a fraction.
Proportion: An equation stating that two ratios are equal.

2. Determine whether the ratios form proportions
Therefore, the ratios form a proportion.

3. Means & Extremes
In a proportion, the product of the extremes is equal to the product of the means.
If then ad = bc. Cross Multiply.

4. Use cross products (cross multiplication) to determine whether each pair of ratios forms a proportion.
No, so it is not a proportion.
Yes, so it is a proportion.

5. Solve Using Cross Multiplication

6. Use rates 8(2435) = 5n 19480 = 5n 19480/5 = 5n/5 3896 = n 3896 turns
The gear on a bicycle is 8:5. This means that for every 8 turns of the pedals, the wheel turns 5 times. Suppose the bicycle wheel turns about 2435 times during a trip. How many times would you have to crank the pedals during the trip?
8(2435) = 5n
19480 = 5n
19480/5 = 5n/5
3896 = n
3896 turns

7. Using a Scale Drawing
In a road atlas, the scale for the map of Connecticut is 5 inches = 41 miles. The scale for the map of Texas is 5 inches = 144 miles. What are the distances in miles represented by 2 ½ inches on each map?
Connecticut:
Texas:

8. Homework #15
Practice Worksheet 2.6
Quiz Tuesday