Lesson 2­6 Ratios and Proportions with answers.notebook
October 02, 2014
Questions/Main Ideas Lesson 2­6 Ratios and Proportions
ratio ­ the comparison of two numbers by division
x to y, x : y, x
y
proportion ­ an equation stating that two ratios are equal
Questions/Main Ideas Examples
49
7
1. Determine whether the ratios and form a 56
8
proportion.
2. Use cross products to determine whether each pair of ratios form a proportion
a.
b.
0.25 and 1.25
2
0.6
4 and
5
16
20
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Lesson 2­6 Ratios and Proportions with answers.notebook
October 02, 2014
Questions/Main Ideas
On the previous problem, 4 and 20 are called the extremes. 5 and 16 are called the means.
Means­Extremes Property
In a proportion, the product of the extremes is equal to the product of the means.
If a = c , then ad = bc.
b d
Questions/Main Ideas Examples
Solve the proportion
3. n 3
=
12
8
5.
4. a = 5 45
15
x+4 = 3 4
12
rate ­ the ratio of two given measurements having different units of measure
unit rate ­ a rate that tells how many of one item is being compared to 1 of another item
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Lesson 2­6 Ratios and Proportions with answers.notebook
October 02, 2014
Questions/Main Ideas Example 5
The gear on a bicycle is 8 : 5 meaning for every 8 turns of the pedals, the wheel turns 5 times. If the wheel turns 2435 times, how many times would you have to crank the pedals?
Questions/Main Ideas scale ­ the ratio or rate used when making a model of something that is too large or too small to be conveniently shown at actual size
Example 6
In the road atlas, the scale for the map of Connecticut is 5 inches = 41 miles. For Texas, 5 inches = 144 miles. What distances are represented by 2.5 inches on each map?
3
Lesson 2­6 Ratios and Proportions with answers.notebook
October 02, 2014
4