Proportions

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal.

Front

How do you determine if two ratios form a proportion?

Back

Two ratios form a proportion if the cross products are equal.

Front

If 13 out of 20 homes have a personal computer, how do you find the expected number of homes with a computer on a street with 60 homes?

Back

Set up a proportion: 13/20 = x/60, then solve for x.

Front

What is the formula to find the missing value in a proportion?

Back

If a/b = c/d, then ad = bc.

Front

How many sticks of pepperoni are needed for 36 pizzas if 14 sticks are needed for 28 pizzas?

Back

18 sticks.

Front

If Mr. Dulin runs 5 miles in 42 minutes, how long will it take him to run 25 miles?

Back

210 minutes.

Front

What is a ratio?

Back

A ratio is a comparison of two quantities by division.

Front

What is the relationship between ratios and proportions?

Back

Proportions are equations that show two ratios are equivalent.

Front

How can you check if a pair of ratios is a proportion?

Back

Cross-multiply and see if the products are equal.

Front

What is the cross product of the ratios 3/4 and 6/8?

Back

3 * 8 = 24 and 4 * 6 = 24, so they are proportional.