Unit 3 Proportionality and Ratios

What is the constant of proportionality for this table?

• $1/9 per hour

• $9 per hour

• $8 per hour

Identify the constant of proportionality.

• k = 1/90

• k = 90

• k = 1/30

• k = 30

• none (not proportional)

To make pink paint, Sylvia mixes 7 cups of white paint to every 3 cups of red paint. Which table shows possible values of w, the number of cups of white paint Sylvia uses, and r, the number of cups of red paint?

• 
• 
• 
• 

The 6th grade took a field trip to the movies. The table shows the price of popcorn based on the quantity purchased. How much would it cost for 20 bags of popcorn? 

• 50

• 55

• 60

• 65

If the ratio of cats to dogs in a pet store is 3:4, how many cats are there if there are 12 dogs?

• 9

• 16

• 8

• 10

Answer explanation

To find the number of cats, use the ratio 3:4. Since there are 12 dogs, divide 12 by the 4 in the ratio, since that is the number that represents dogs. When you divide 12 by 4, you get 3, telling you to multiply the 3 in the ratio, representing the cats, by 3. Therefore, there are 9 cats.

If the ratio of cats to dogs is 3:4, how many cats are there if there are 20 dogs?

• 15 cats

• 25 cats

• 30 cats

• 10 cats

If the ratio of cats to dogs in a pet store is 3:4, and there are 12 cats, how many dogs are there?

• 16

• 14

• 18

• 20

If the ratio of boys to girls in a class is 5:6 and there are 30 girls, how many boys are there?

• 25

• 20

• 24

• 28

If a recipe calls for a ratio of 2 cups of flour to 3 cups of sugar, how many cups of sugar are needed if 8 cups of flour are used?

• 6

• 10

• 12

• 14

• 60

• 65

• 70

• 75