3.4 Solving Proportions.notebook
A ratio is a comparison of two numbers
a to b
a : b
a
b
October 12, 2011
A ratio is a comparison of two numbers
a : b
a to b
a
b
1. 23 out of 30 students got an A on the test
Examples: "I got 21 out of 24 questions correct."
2. A canary's heart beats 200 times in 12 seconds
21 to 24 21:24
21 24
Oct 14­8:36 PM
Oct 14­8:36 PM
A proportion is an equation that states that two ratios are equal
a c
=
b d
Oct 14­8:43 PM
A proportion is solved by cross multiplication
(multiply diagonally)
a c
=
b d
ad = cb
2.
y 4
=
12 7
Oct 14­8:43 PM
(multiply diagonally)
2 ? 8
=
3 12
Oct 14­8:43 PM
x 5
=
8 6
A proportion is solved by cross multiplication
a c
=
b d
ad = cb
"a is to b as c is to d"
1.
3. You traveled 186 miles in 3 hours 3.
Jennifer estimates that two out of every three students in her class will attend the class party. How many students out of 750 in her class can you predict will attend?
50 15
=
18 m
Oct 14­8:48 PM
1
3.4 Solving Proportions.notebook
Jordan can text 25 letters in 10 seconds. How many seconds will it take him to text 20 letters?
October 12, 2011
There are 25 M&M's in a 2oz bag. How many M&M's will be in a 16oz bag?
A box of cereal weighting 354 grams contains 20 grams of fat. Find the grams of fat in the recommended serving size of 55 grams.
There are 600 calories in a 6oz bagel. How many calories in a 3oz bagel?
Oct 1­11:31 AM
Oct 1­11:32 AM
Solve the proportions:
Example 1:
Example 2:
Homework #16
3 = x ­ 3
6
8
3 = 5
w + 6 w ­ 4
Pg 146 #16­24, 26­28
3.1­3.3 MINI TEST FRIDAY!!!
Oct 15­7:21 AM
Oct 1­1:03 PM
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