Ratios
Proportions
Real World Ratios
Percents, Fractions, Decimals
Percent Proportion
100
Out of 20 friends, 7 wear Nike shoes. The rest wear Reebok. What is the ratio of students who wear Nike shoes to those who wear Reebok?
20 - 7 = 13 Reebok Shoes
Nike: Reebok
7 : 13
This is a PART TO PART ratio.
100
Do the ratios form a proportion? Prove it!
Yes! The cross products both equal 24!
100
A recipe calls for 1/2 cup of milk. How much milk would you need if you were DOUBLING the recipe?
MULTIPLY BY 2!
1 cup milk
100
Change the following to decimals:
A) 1/2
B) 1/5
C) 1/4
D) 1/10
These are decimals you should memorize!
A) 1/2 = 0.5
B) 1/5 = 0.2
C) 1/4 = 0.25
D) 1/10 = 0.1
100
What IS the percent proportion equation?
200
In a certain math class, 12 students wore a jacket to class. 15 students did not wear a jacket. What is the ratio of students who didn't wear a jacket to the total number of students in the math class?
12 + 15 = total # students = 27
No Jacket : Total Students
15 : 27
This is a PART TO WHOLE ratio.
200
Do the ratios form a proportion? Prove it!
No! The cross products are NOT equal!
200
A recipe calls for 2/3 cup of sugar. How much sugar would you need if you were HALVING the recipe?
*MULTIPLY BY 1/2
(2/3) x (1/2) = 2/6 = 1/3 cup sugar
*OR DIVIDE BY 2!
200
Change 2/9 to a decimal.
2/9 = 0.2222.....
Answer:
0bar .2
200
What is 12% of 20?
short cut: 0.12 x 20 = 2.4
percent proportion:
300
What is the ratio of Additional Cost to the number of Pizza Toppings?
Cost : Toppings
$2 : 1 topping
300
Solve the proportion:
x = 4
300
A 24 oz jar of pickles cost $2.49. What is the unit rate?
$2.49 / 24 oz = 0.10 = 10 cents per ounce
You can use DESMOS to do the division!
300
Change 3.5 to a percent.
3.5 x 100 = 350%
MULTIPLY BY 100!
Or, just move the decimal point two places to the RIGHT!
300
What percent is 3 of 15?
3/15 = 0.20 = 20%
Percent Proportion:
400
Find the missing numbers in the ratio table:
400
Solve the proportion:
x = 14
400
A 9.9 oz bag of Blue Heat Takis cost $3.89. What is the unit rate?
$3.89 / 9.9 oz = 0.39 = 39 cents per ounce
You can use DESMOS to do the division!
400
Change 15% to a decimal.
15/100 = 0.15
DIVIDE BY 100!
Or, just move the decimal point (You can't see it, but it's technically behind the 15!) two places to the LEFT!
400
4 is 32% of what number?
Percent Proportion:
500
What does the information in the ratio table mean?
Find the missing values in the ratio table.
This table is comparing the amount of time a person spends reading verses watching TV.
For every 1 minute spent reading, this person spends 4 minutes watching TV.
500
What MUST be true about the relationship between a, b, c, and d if these two ratios form a proportion?
A) ab = cd
B) bd = ac
C) ad = bc
C) ad = bc
If two ratios form a proportion (are equal), their cross products will be equal!
500
Which is the better deal?
A) 18 candy bars for $21.49
B) 12 candy bars for $14.16
A) unit rate = $21.49 / 18 = $1.19 per candy bar
B) unit rate = $14.16 / 12 = $1.18 per candy bar
OPTION B IS THE BETTER DEAL!
Use Desmos to help with the division!
500
Change 25% to a fraction.
25% = 25/100 = 1/4
500
11.5 is 14.2% of what number?
Round to the nearest hundredth.
Answer: 80.99
Percent Proportion:
