8th Grade
Mathematics
Unit: 04 Lesson: 01
Unit Rates with Purchasing (pp. 1 of 2)
Solve the following problems.
1. Mrs. Holt bought 5 bags of toys for a science experiment that cost $6.45.
a. What is the unit rate per bag? Justify your response.
b. At this rate, how much would Ms. Pena pay for 7 bags of toys? Justify your response.
2. Ms. Groves bought 30 packages of “fun-size” N&Ns for her students for $6.60.
a. What is the unit rate per “fun-size” bag? Justify your response.
b. Mrs. Bano bought 40 packages of “fun-size” N&Ns for $10.00. Did Mrs. Bano get a better
buy or worse buy than Ms. Groves? Justify your response.
3. Lupe went to the Trade Center on Saturday and bought 15 baseball cards for $13.05. What is
the unit rate of the baseball cards? Justify your response.
4. If Braulio bought 34 spinners for $5.44, then how much would he pay for 20 spinners? Estimate
the unit rate, solve the problem. Write a paragraph to explain the process and justify your
response.
©2010, TESCCC
08/01/10
8th Grade
Mathematics
Unit: 04 Lesson: 01
Unit Rates with Purchasing (pp. 2 of 2)
Solve the following problems.
5. The price of a gallon of milk is $3.76 and the price of a quart of milk is $1.05. Which of the two
quantities of milk has the best unit price? Justify your response.
6. If approximately 3.79 liters equals 1 gallon, approximately how many liters are in 2.5 gallons?
©2010, TESCCC
08/01/10
8th Grade
Mathematics
Unit: 04 Lesson: 01
Unit Rates with Purchasing (pp. 1 of 2) KEY
Solve the following problems.
1. Mrs. Holt bought 5 bags of toys for a science experiment that cost $6.45.
a. What is the unit rate per bag? Justify your response.
1

$6.45
5 = $1.29 Unit rate is $1.29 per bag
5 bags  1
1 bag
5
b. At this rate, how much would Ms. Pena pay for 7 bags of toys? Justify your response.
$1.29 per bag times 7 bags = $9.03
2. Ms. Groves bought 30 packages of “fun-size” N&Ns for her students for $6.60.
a. What is the unit rate per “fun-size” bag? Justify your response.
1

$6.60
30 = $0.22 Unit rate is 22 cents per bag
30 bags  1
1 bag
30
b. Mrs. Bano bought 40 packages of “fun-size” N&Ns for $10.00. Did Mrs. Bano get a better
buy or worse buy than Ms. Groves? Justify your response.
1

$10.00
40 = $0.25 Unit rate is 25 cents per bag  worse buy
40 bags  1
1 bag
40
3. Lupe went to the Trade Center on Saturday and bought 15 baseball cards for $13.05. What is
the unit rate of the baseball cards? Justify your response.
1

$13.05
15 = $0.87 Unit rate is 87 cents per card
15 cards  1
1 card
15
4. If Braulio bought 34 spinners for $5.44, then how much would he pay for 20 spinners? Estimate
the unit rate, solve the problem. Write a paragraph to explain the process and justify your
response.
Estimate: Between $0.10 and $0.20 because $0.10 per spinner for 34 spinners is $3.40 and
$0.20 per spinner for 34 spinners is $6.80 and it states he paid $5.44 for 34 spinners.
1

$5.44
34 = $0.16 Unit rate is16 cents per spinner.
34 spinners  1
1 spinner
34
Cost for 20 spinners: $0.16 per spinner times 20 spinners = $3.20
1
Found the unit rate by multiplying both quantities by
because this gives the price for 1
34
spinner. The estimated price was between 10 cents and 20 cents so 16 cents is reasonable.
Multiplied 16 cents per spinner by 20 spinners to determine the total cost. This is reasonable
because this cost is less than $5.44 for 34 spinners.
©2010, TESCCC
08/01/10
8th Grade
Mathematics
Unit: 04 Lesson: 01
Unit Rates with Purchasing (pp. 2 of 2) KEY
Solve the following problems.
5. The price of a gallon of milk is $3.76 and the price of a quart of milk is $1.05. Which of the two
quantities of milk has the best unit price? Justify your response.
1
gallon
4 quarts
$3.76
$1.05
4
Unit rate:
Unit rate:
Unit rate:
Unit rate:
1 quart
1 gallon
1 gallon
1 quart
1
gallon
$3.76
? Price $0.94
4
=
•
;
1 quart
1 gallon
1 quart 1 quart
The gallon of milk costs $0.94 a quart and is the better buy compared to the $1.05 for a quart
of milk.
6. If approximately 3.79 liters equals 1 gallon, approximately how many liters are in 2.5 gallons?
Unit rate:
3.79 liters
1 gallon
Proportion:
3.79 liters
? liters
3.79 liters  2.5
? kilometers
=
;
=
; ? = 9.475 liters
1 gallon
2.5 gallons 1 gallon  2.5
2.5 gallons
Equation: y = 3.79 x, where y represents the number of liters and x represents the number of
gallons; y = 3.79(2.5); y = 9.475 liters
©2010, TESCCC
08/01/10