6th Grade Math Textbook, Fundamentals

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6-2

Key Concept

is a ratio that compares two unlikequantities.

is a ratio that is simplified to have a denominator of 1 unit.

It compares an amount, x, to one unit:.

is the price per unit of an item.

Unit rate

Unit cost

Rate

x

1

Update your skills. See pages 412 XIII, 413 XIV.

Unit Rate and Unit Cost

Objective To write rates •To find unit rates • To use unit cost to determine the

better or best buy • To compare rates

The price list at the right shows the sale prices for DVDs

in three different video stores. Which store has the

best buy?

To find the best buy, use the given price at each store to

find the unit rate, or the cost of one DVD. Then compare

the unit costs.

Which is the better buy?

• Write each rate. Divide to find the unit rate and unit cost.

$6.10

$7.02

• Compare unit costs: $6.10, $7.02
  $6.10 $7.02

So buying a group of 7 tickets is the better buy.

cost

number of tickets

$63.18

9

$7.02

1

$6.096

1

$42.67

7

cost

number of tickets

1

Write each rate. Then divide the total cost by the number of units

to find the unit cost.

Compare: $9.33, $8.25, $9.50 The least cost for one DVD is $8.25.

So DVD Exchange has the best buy.

Abe’s DVD

Rate: 



Unit rate: $9.33 per DVD

Unit cost: $9.33

$27.99

3

$9.33

1

$27.99

3

cost

number of

DVD Exchange

Rate: 



Unit rate: $8.25 per DVD

Unit cost: $8.25

cost

number of

$33

4

$8.25

1

$33

4

DVD City

Rate: 



Unit rate: $9.50 per DVD

Unit cost: $9.50

cost

number of

$9.50

1

$47.50

5

$47.50

5