Proportional Relationships

What is the value of the missing number?

• 15

• 20

• 25

• 30

There are 4 trucks for every 5 cars in a parking lot. How many trucks and cars could be in the parking lot?

• 64 trucks and 80 cars

• 72 trucks and 73 cars

• 84 trucks and 100 cars

• 96 trucks and 110 cars

Seventy-five 6th-grade students chose to watch a movie on the last day of school. This is 25% of the 6th-grade class. How many total students are in the 6th grade?

• 100

• 200

• 300

• 400

A restaurant orders corn tortillas and flour tortillas. The ratio of the number of corn tortillas to the number of flour tortillas is 2 : 3. What is the ratio of the number of flour tortillas to the total number of tortillas?

• 3 : 8

• 3 : 5

• 2 : 8

• 2 : 5

What is the constant of proportionality (in miles per hour) based on the table?

• 45

• 90

• 135

• 2

A survey in a school found that 60 students own a bicycle. If this represents 30% of all students, how many students are in the school?

• 180

• 200

• 220

• 240

What is the constant of proportionality?

• $3

• $4

• $2

• $9

If the ratio of red balls to blue balls in a bag is 5:3, how many blue balls are there if there are 20 red balls?

• 12

• 15

• 8

• 10

Answer explanation

If the ratio of red balls to blue balls is 5:3, and there are 20 red balls, set up an equality like this: 5/3 = 20/x. To get from 5 in the left numerator to 20 in the right numerator, multiply 5*4. Since the numerator is multiplied by 4, the denominator would also be multiplied by 4. 3*4 = 12.

If the ratio of pencils to pens in a box is 7:5, how many pens are there if there are 21 pencils?

• 15

• 18

• 12

• 14

Answer explanation

To find the number of pens, set up fractions as an equality like this: 7/5 =21/x. 7*3 is 21, so multiply the 5 by 3 as well to get the number of pens, 15.

A recipe calls for 3 cups of flour for every 4 cups of sugar. If you want to use 6 cups of sugar, how many cups of flour do you need?

• 4.5

• 5

• 4

• 4.5