Ratio and Proportion

Proportions

Proportions

• A proportion is an equation stating that two ratios (fractions) are equal.

• If a proportion contains a variable, use cross multiplication and single-step algebra to find the missing value.

Multiple Choice

Solve the proportion:

$$\frac{2}{7}=\frac{c}{28}$$  

• 4

• 14

• 8

• 10

Multiple Choice

Solve for the variable k.

$$\frac{k}{6}=\frac{15}{18}$$  

• k = 5
  

• k = 60

• k =  $$\frac{10}{3}$$  

• k = 90

In order to solve proportions, we will use cross multiplication which is something you have already seen.

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​Solving Proportions

Multiple Choice

Is this proportion true?

$$\frac{1}{6}=\frac{5}{30}$$  

• Yes, this is true

• No, this is not true

• I cannot answer the equation from the information given

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

What is the ratio in the figure?

• 40 : 6

• 35 : 5

• 40 : 5

• 35 : 6

Multiple Choice

What is the ratio in the figure?

• 27 : 72

• 24 : 64

• 21 : 56

• 18 : 48