Ratio and Proportions

Ratios & Proportions: Review

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When two ratios are equal, we say they form a proportion.  You can tell if two ratios are equal by comparing the cross products.

Multiple Choice

$$\frac{10}{16}\ \ \ \ \ \frac{5}{8}$$  

• $$=$$  

• $$\ne$$  

Multiple Choice

$$\frac{4}{8}\ \ \ \ \ \frac{2}{3}$$  

• $$=$$  

• $$\ne$$  

Multiple Choice

$$\frac{6}{8}\ \ \ \ \ \frac{9}{12}$$  

• $$=$$  

• $$\ne$$  

Multiple Choice

$$\frac{12}{20}\ \ \ \ \ \frac{3}{5}$$  

• $$=$$  

• $$\ne$$  

Multiple Choice

$$\frac{10}{12}\ \ \ \ \ \frac{15}{18}$$  

• $$=$$  

• $$\ne$$  

Multiple Choice

$$\frac{10}{12}\ \ \ \ \ \frac{2}{3}$$  

• $$=$$  

• $$\ne$$  

Multiple Choice

$$\frac{5}{9}\ \ \ \ \ \frac{15}{27}$$  

• $$=$$  

• $$\ne$$  

Multiple Choice

Do these ratios form a proportion?

$$\frac{3}{12}\ \ \ \ \ \frac{10}{30}$$  

• yes

•  no

Multiple Choice

Do these ratios form a proportion?

$$\frac{7}{16}\ \ \ \ \ \frac{42}{66}$$  

• yes

•  no

Multiple Choice

Do these ratios form a proportion?

$$\frac{11}{12}\ \ \ \ \ \frac{66}{72}$$  

• yes

•  no

You can use cross multiplication to find an unknown term in a proportion.