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2.7 solving proportions
Objective: 1. Solve problems using proportions
Ratio: A comparison of two numbers, usually written as a fraction.
Proportion: --An equation stating that two ratios are equal
--(or two equal fractions)
Where b ≠ 0 and d ≠ 0.
What do you notice happens when you multiply the diagonals on the following proportion?
Please solve for x in each of the following.
3 = x
5 20
12 = x
4 = 10
7 x
17.5 = x
7 = 49
X 56
8 = x
3 (20) = 5(x) 7(56) = 49(x) 7(10) = 4(x)
solve for x
4 (x – 8) = 5(x + 3)
4x – 32 = 5x + 15- 5x - 5x______-1x – 32 = 15 + 32 +32
-1x = 47-1x = 47-1 -1 x = - 47
Using a proportion to solve a problem.
A portable media player has 2 gigabytes of storage and can hold about 500 songs. A similar but larger media player has 80 gigabytes of storage. About how many songs can the larger media player hold?
Know Need Plan Know Need Plan
A portable media player has 2 gigabytes of storage and can hold about 500 songs. A similar but larger media player has 80 gigabytes of storage. About how many songs can the larger media player hold?
A portable media player has 2 gigabytes of storage and can hold about 500 songs. A similar but larger media player has 80 gigabytes of storage. About how many songs can the larger media player hold?
2 gigabytes holds 500 songs
Larger player has 80 gigabytes
Know Need Plan The number of songs the larger player holds
Know Need Plan Write a proportion and solve.
2x = 500(80)
2x = 40,0002x = 40,0002 2
x = 20,000
The larger media player holds 20,000 songs
A portable media player has 2 gigabytes of storage and can hold about 500 songs. A similar but larger media player has 80 gigabytes of storage. About how many songs can the larger media player hold?
homework
• Pg 127: 10-40 evens, 51, 52
• Note: showing work is optional through 24, required past that.