Analyzing Cost Functions: Real-Life Comparisons for 8th Graders

A car rental company charges a flat fee of $30 plus $0.20 per mile driven. Another company charges $15 plus $0.50 per mile. Which company is cheaper for a trip of 100 miles?

• Both companies charge the same amount.

• The first company is cheaper.

• The second company is cheaper.

• The first company charges $15 plus $0.50 per mile.

A gym charges a monthly fee of $40 plus $5 for each class attended. Another gym charges a flat rate of $60 for unlimited classes. After how many classes will the first gym become more expensive?

• 7

• 10

• 3

• 5

A phone plan costs $25 per month plus $0.10 per text message. Another plan costs $40 per month with unlimited texts. For how many text messages is the first plan cheaper?

• 75

• 200

• 100

• 149

A bakery sells cupcakes for $3 each or a box of 12 for $30. How many cupcakes do you need to buy for the box to be a better deal?

• 15

• 12

• 11

• 10

A subscription service charges $10 per month or $100 for a year. How many months do you need to subscribe for the yearly plan to be cheaper?

• 10 months

• 9 months

• 11 months

• 12 months

A taxi charges a base fare of $2.50 plus $1.50 per mile. A rideshare service charges $1.00 per mile with no base fare. After how many miles does the taxi become more expensive?

• 3 miles

• 10 miles

• 5 miles

• 7 miles

A school is planning a field trip. The bus company charges $200 for the bus plus $5 per student. Another company charges $300 flat. How many students make the first option more expensive?

• 25

• 22

• 20

• 21

A farmer sells apples for $1.50 per pound or $12 for a 10-pound bag. How many pounds do you need to buy for the bag to be a better deal?

• 8 pounds

• 9 pounds

• 7 pounds

• 10 pounds

A streaming service offers a monthly subscription for $12 or an annual subscription for $120. How many months do you need to subscribe for the annual plan to be cheaper?

• 11 months

• 10 months

• 9 months

• 12 months

A local pool charges $5 for a day pass or $40 for a season pass. How many days do you need to go for the season pass to be worth it?

• 8 days

• 10 days

• 5 days

• 15 days