Upload
others
View
9
Download
0
Embed Size (px)
Citation preview
Geo 71 Lesson with notes 3rd b.notebook
1
February 16, 2016
Feb 115:07 PM
71 Ratios and Proportions
Learning TargetsI can write ratiosI can write and solve proportions
If the dimensions of the screen shown are 32 inches by 18 inches, is the screen standard or high definition?
Would a standard television have a narrower or wider screen?
What is the height of a high definition television that is 48 inches wide?
Feb 1611:28 AM
Geo 71 Lesson with notes 3rd b.notebook
2
February 16, 2016
Feb 117:47 PM
Ratio: a comparison of two numbers using division.
A ratio can by written as a to b, a : b, or a/b, where b ≠ 0.
Always written in simplest form (reduce fraction)
Feb 118:01 PM
Geo 71 Lesson with notes 3rd b.notebook
3
February 16, 2016
Feb 118:03 PM
Example 1:
1. The number of students that participate in sports programs at Central High School is 520. The total number of students in the school is 1850. Find the athletetostudent ratio to the nearest tenth.
2. In a high school, there are 190 teachers and 2650 students. What is the approximate studetteacher ratio at his school?
Feb 118:11 PM
Extended ratios: ratios can be used to compare three or more quantities.
a : b : c means that the ratio of the first two quantities is a : b, the ratio of the last two quantities is b : c, and the ratio of the first and last quantities is a : c.
Geo 71 Lesson with notes 3rd b.notebook
4
February 16, 2016
Feb 118:14 PM
Feb 118:16 PM
Example 2:
3. In ΔEFG, the ratio of the measures of the angles is 5 : 12 : 13, and the perimeter is 90 centimeters. Find the measures of the angles.
4. In a triangle, the ratio of the measures of the sides is 3 : 3 : 8 and the perimeter is 392 inches. Find the length of the longest side of the triangle.
Geo 71 Lesson with notes 3rd b.notebook
5
February 16, 2016
Feb 118:18 PM
Proportion: an equation stating two or more ratios are equal.
The extremes are the top left and its diagonalThe means are the bottom left and its diagonal
Feb 118:23 PM
Cross products: product of the extremes (ad) and the means (bc).
Geo 71 Lesson with notes 3rd b.notebook
6
February 16, 2016
Feb 118:25 PM
Feb 118:26 PM
Example 3: Solve each proportion.
5. 6 = 9 6. 4x 5 = 26 7. x = 11 18.2 y 3 6 4 6
8. 4 = 6 9. 7 = 9 7 2y + 5 z 1 z + 4
Geo 71 Lesson with notes 3rd b.notebook
7
February 16, 2016
Feb 118:31 PM
Feb 118:35 PM
Example 4:
10. Monique randomly surveyed 30 students from her class and found that 18 had a dog or a cat for a pet. If there are 870 students in Monique's school, predict the total number of students with a dog or a cat.
11. In an experiment, students netted butterflies, recorded the number with tags on their wings, and then released them. The students netted 48 butterflies and 3 of those had tagged wings. Predict the number of butterflies that would have tagged wings out of 100 netted.
Geo 71 Lesson with notes 3rd b.notebook
8
February 16, 2016
Feb 118:38 PM
Proportions can be written correctly in four different ways.