Lesson 8: How Much for One?

Let’s use ratios to describe how much things cost.

8.1: Number Talk: Remainders in Division

Find the quotient mentally.

$246\div 12$

8.2: Grocery Shopping

  1. Eight avocados cost \$4.

    1. How much do 16 avocados cost?
    2. How much do 20 avocados cost?
    3. How much do 9 avocados cost?
  2. Twelve large bottles of water cost \$9.

    1. How many bottles can you buy for \$3?
    2. What is the cost per bottle of water?
    3. How much would 7 bottles of water cost?
  3. A 10-pound sack of flour costs \$8.

    1. How much does 40 pounds of flour cost?
    2. What is the cost per pound of flour?

Here is an applet you can use if you choose to.

GeoGebra Applet ycJSQpXT

8.3: More Shopping

  1. Four bags of chips cost \$6.

    1. What is the cost per bag?

    2. At this rate, how much will 7 bags of chips cost?

  2. At a used book sale, 5 books cost \$15.
    1. What is the cost per book?

    2. At this rate, how many books can you buy for \$21?

  3. Neon bracelets cost \$1 for 4.
    1. What is the cost per bracelet?

    2. At this rate, how much will 11 neon bracelets cost?

  4. Pause here so your teacher can review your work. Next, your teacher will assign you one of the problems.

  5. Create a visual display that shows your solution to your assigned problem. Be prepared to share your solution with the class.

Here is an applet you may use if you choose to.

GeoGebra Applet ycJSQpXT

Summary

The unit price is the price of 1 thing—for example, the price of 1 ticket, 1 slice of pizza, or 1 kilogram of peaches.

If 4 movie tickets cost \$28, then the unit price would be the cost per ticket. We can create a double number line to find the unit price.

"A double number line with 6 evenly spaced tick marks. The top number line is labeled "cost in dollars" and the numbers  0, 7, 14, 21, 28, and 35 are indicated. The bottom number line is labeled "number of tickets" and the numbers  0, 1, 2, 3, 4, and 5 are indicated. There is a circle around the numbers 7 and 1 and a second circle around 28 and 4."

This double number line shows the cost for 1 ticket is \$7. We can also find the unit price by dividing, $28 \div 4 = 7$, or by multiplying, $28 \boldcdot \frac14 = 7$.

Practice Problems ▶

Glossary

unit price

unit price

The unit price is the cost for one item or one unit of measure.