Evaluating Function Values: Real-World Problems for 8th Graders

1. A function f(x) = 3x + 2 represents the cost in dollars of x pounds of apples. What is the cost of 5 pounds of apples?

• 10 dollars

• 25 dollars

• 17 dollars

• 12 dollars

2. The function g(t) = 2t^2 - 4t models the height in meters of a ball thrown upward after t seconds. What is the height of the ball after 3 seconds?

• 10

• 4

• 6

• 8

3. A function h(n) = 4n - 1 describes the number of books read by a student in n weeks. How many books will the student have read after 6 weeks?

• 20

• 30

• 23

• 25

4. The function p(x) = x/2 + 10 represents the temperature in degrees Celsius at x hours after noon. What is the temperature at 4 PM (4 hours after noon)?

• 8 degrees Celsius

• 10 degrees Celsius

• 12 degrees Celsius

• 15 degrees Celsius

5. A function q(y) = 5y + 3 models the distance in kilometers a car travels after y hours. How far does the car travel after 2 hours?

• 15 kilometers

• 8 kilometers

• 10 kilometers

• 13 kilometers

6. The function r(z) = z^2 - 5 models the profit in dollars from selling z items. What is the profit when 6 items are sold?

• 40

• 31

• 25

• 18

7. A function s(m) = 7 - 2m represents the remaining balance in a bank account after m months. What is the balance after 3 months?

• 1

• -1

• 5

• 0

8. The function t(x) = 10x + 15 describes the total cost in dollars of x movie tickets. What is the total cost for 4 tickets?

• 45

• 55

• 60

• 50

9. A function u(k) = 3k^2 + 2k models the number of visitors to a park after k days. How many visitors are there after 5 days?

• 75

• 85

• 50

• 100

10. The function v(w) = 12 - w represents the amount of water left in a tank after w hours. How much water is left after 7 hours?

• 5

• 8

• 3

• 10