Solving Proportions

Writing & Solving Proportions Using Proportional Reasoning

TAKE NOTES AS YOU COMPLETE THIS LESSON​

Solving a Proportion

You can use cross multiplication to solve a proportion problem

• Step 1:

  Multiply Top Left and Bottom Right

• Step 2:

  Multiply Bottom Left and Top Right

Solving a Proportion

• Then divide to find the missing number

Another Method:

​A proportion is 2 equivalent ratios.

​We can use proportional reasoning to solve problems.

Another Method:

​A proportion is 2 equivalent ratios.

​We can use proportional reasoning to solve problems.

In an exercise class, the ratio of men to women is 3:4. If there are 21 men, how many women are in the exercise class?

Set up a proportion of men over women.​

In an exercise class, the ratio of men to women is 3:4. If there are 21 men, how many women are in the exercise class?

In an exercise class, the ratio of men to women is 3:4. If there are 21 men, how many women are in the exercise class?

​3 x 7 = 21

4 x 7 = 28​

​There are 28 women in the class.

The ratio of boys to girls is 3 to 2. If there are 12 boys, how many girls are there?

Multiple Choice

The ratio of boys to girls is 3 to 2. If there are 12 boys, how many girls are there?

• 8

• 4

• 16

• 11

Multiple Choice

Solve for x 

• x = 1/10
• x = 10
• x = 4
• x = 5

Multiple Choice

In a certain apartment building, the ratio of people to cars is 3:5. If there are 30 people, how many cars are there?

• 35

• 60

• 18

• 50

Multiple Choice

Solve the proportion.

$$\frac{y}{3}=\frac{48}{9}$$  

• y = 16

• y = 144

• y = 3

• y = 5.3

Multiple Choice

Solve the proportion.

$$\frac{3}{q}=\frac{5}{6}$$  

• q = 10

• q = 3.6

• q = 18

• q = 2.5

Multiple Choice

Gregory bought 6 post cards for $3. How much would 10 post cards cost?

• $4.50

• $5.00

• $0.50

• $20.00

Multiple Choice

Solve for X $$\frac{x}{8}=\frac{25}{40}$$  

• 5

• 12.8

• 200

• 480

Multiple Choice

Solve for X $$\frac{4}{7}=\frac{20}{x}$$  

• 35

• 11.43

• 140

• 80

Multiple Choice

Solve for x

$$\frac{3}{5}=\frac{24}{x}$$  

• $$x=16$$  

• $$x=120$$  

• $$x=40$$  

Multiple Choice

Solve for x

$$\frac{4}{5}=\frac{8}{x}$$  

• x = 8

• x = 10

• x = 4

• x = 5

Multiple Choice

$$\frac{x}{5}=\frac{8}{10}$$

Solve for x

• x=7

• x=4

• x=2

• x=3

Multiple Choice

 

$$\frac{21}{x}=\frac{6}{8}$$  

• x = 6

• x = 25

• x = 28

• x = 17