Exploring Function Domains & Costs: Word Problems for 8th Graders

1. A car rental company charges a flat fee of $30 plus $0.20 per mile driven. If the total cost is represented by the function C(m) = 30 + 0.20m, what is the domain of this function?

• (-∞, 0)

• [0, ∞)

• (0, 100)

• [0, 100]

2. If you drive 150 miles, what is the total cost of renting the car? Use the function C(m) = 30 + 0.20m to find your answer.

• 75

• 60

• 50

• 100

3. A gym charges a monthly fee of $25 plus $5 for each class attended. The total cost can be expressed as C(c) = 25 + 5c. What is the domain of this function in terms of classes attended?

• c < 0

• c is any real number

• c >= 0, where c is a non-negative integer

• c is a negative integer

4. If you attend 8 classes in a month, what will your total cost be? Calculate using the function C(c) = 25 + 5c.

• 80

• 50

• 65

• 100

5. A phone plan costs $40 per month plus $0.10 for each text message sent. The cost can be modeled by the function C(t) = 40 + 0.10t. What is the domain of this function?

• t <= 10

• t >= 0

• t = 0

• t < 0

6. If you send 200 text messages in a month, what will your total cost be? Use the function C(t) = 40 + 0.10t to find your answer.

• 50

• 80

• 100

• 60

7. A bakery sells cupcakes for $3 each and charges a $10 delivery fee. The total cost can be expressed as C(x) = 10 + 3x. What is the domain of this function?

• x < 0

• x <= 10

• x = 5

• x >= 0

8. If you order 12 cupcakes, what will your total cost be? Calculate using the function C(x) = 10 + 3x.

• 50

• 30

• 40

• 46

9. A subscription service charges $15 per month plus $2 for each movie rented. The cost can be modeled by C(m) = 15 + 2m. What is the domain of this function?

• m < 0

• m ∈ R

• m >= 0, m ∈ Z+

• m = 0

10. If you rent 5 movies in a month, what will your total cost be? Use the function C(m) = 15 + 2m to find your answer.

• 25

• 30

• 20

• 35