Lesson 8: How Much for One?
Let’s use ratios to describe how much things cost.
Illustrative Math Unit 6.2, Lesson 8 (printable worksheets)
Lesson 8 Summary
The following diagram shows how to use a double number line diagram to find the unit price and solve word problems.
8.1 Number Talk: Remainders in Division
Find the quotient mentally.
246 ÷ 12
- Eight avocados cost $4.
a. How much do 16 avocados cost?
b. How much do 20 avocados cost?
c. How much do 9 avocados cost?
- Twelve large bottles of water cost $9.
a. How many bottles can you buy for $3?
b. What is the cost per bottle of water?
c. How much would 7 bottles of water cost?
- A 10-pound sack of flour costs $8.
a. How much does 40 pounds of flour cost?
b. What is the cost per pound of flour?
Open applet for double number line
- Four bags of chips cost $6.
a. What is the cost per bag?
b. At this rate, how much will 7 bags of chips cost?
- At a used book sale, 5 books cost $15.
a. What is the cost per book?
b. At this rate, how many books can you buy for $21?
- Neon bracelets cost $1 for 4.
a. What is the cost per bracelet?
b. At this rate, how much will 11 neon bracelets cost?
- Pause here so your teacher can review your work. Next, your teacher will assign you one of the problems.
- Create a visual display that shows your solution to your assigned problem. Be prepared to share your solution with the class.
Open applet for double number line
The unit price is the cost for one item or for one unit of measure. For example, if 10 feet of chain link fencing cost $150, then the unit price is 150 ÷ 10, or $15 per foot.
Lesson 8 Practice Problems
- In 2016, the cost of 2 ounces of pure gold was $2,640. Complete the double number line to show the cost for 1, 3, and 4 ounces of gold.
- The double number line shows that 4 pounds of tomatoes cost $14. Draw tick marks and write labels to show the prices of 1, 2, and 3 pounds of tomatoes.
- 4 movie tickets cost $48. At this rate, what is the cost of:
a. 5 movie tickets?
b. 11 movie tickets?
- Priya bought these items at the grocery store. Find each unit price.
a. 12 eggs for $3. How much is the cost per egg?
b. 3 pounds of peanuts for $7.50. How much is the cost per pound?
c. 4 rolls of toilet paper for $2. How much is the cost per roll?
d. 10 apples for $3.50. How much is the cost per apple?
- Clare made a smoothie with 1 cup of yogurt, 3 tablespoons of peanut butter, 2 teaspoons of chocolate syrup, and 2 cups of crushed ice.
a. Kiran tried to double this recipe. He used 2 cups of yogurt, 6 tablespoons of peanut butter, 5 teaspoons of chocolate syrup, and 4 cups of crushed ice. He didn’t think it tasted right. Describe how the flavor of Kiran’s recipe compares to Clare’s recipe.
b. How should Kiran change the quantities that he used so that his smoothie tastes just like Clare’s?
- A drama club is building a wooden stage in the shape of a trapezoidal prism. The height of the stage is 2 feet. Some measurements of the stage are shown here.
What is the area of all the faces of the stage, excluding the bottom? Show your reasoning. If you get stuck, consider drawing a net of the prism.
The Open Up Resources math curriculum is free to download from the Open Up Resources website and is also available from Illustrative Mathematics.
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