A company charges $15 per hour plus a $20 setup fee to rent a bouncy house for 3 hours or less. They charge $12 per hour and no setup fee if the bouncy house is rented for more than 3 hours. Sketch a graph of the piecewise function that models this scenario. Use the graph to select the correct equation for the function where x

is the number of hours and y
is the total cost.(1 point)
Responses

1 answer

To create a piecewise function based on the bouncy house rental costs, we need to define the two scenarios presented in the problem:

  1. For rentals of 3 hours or less:

    • The total cost \( y \) is given by the formula: \[ y = 15x + 20 \] where \( x \) is the number of hours rented (0 ≤ \( x \) ≤ 3).
  2. For rentals of more than 3 hours:

    • The total cost \( y \) is given by the formula: \[ y = 12x \] where \( x \) is the number of hours rented ( \( x \) > 3).

Putting this together, we can write the piecewise function as:

\[ y = \begin{cases} 15x + 20 & \text{if } 0 \leq x \leq 3 \ 12x & \text{if } x > 3 \end{cases} \]

Sketching the Graph

  1. For 0 ≤ x ≤ 3:

    • When \( x = 0 \): \( y = 15(0) + 20 = 20 \) (start at (0, 20)).
    • When \( x = 1 \): \( y = 15(1) + 20 = 35 \).
    • When \( x = 2 \): \( y = 15(2) + 20 = 50 \).
    • When \( x = 3 \): \( y = 15(3) + 20 = 65 \) (line endpoint at (3, 65)).
    • This segment of the graph is a linear equation with a slope of 15.
  2. For x > 3:

    • At \( x = 3 \), \( y = 65 \) (this is where the line transitions).
    • When \( x = 4 \): \( y = 12(4) = 48 \) (this indicates a steep drop).
    • When \( x = 5 \): \( y = 12(5) = 60 \).
    • When \( x = 6 \): \( y = 12(6) = 72 \).
    • This segment of the graph starts at (3, 65) and is a linear equation with a slope of 12.

Summary

  • From (0, 20) to (3, 65), the graph is a line with a steep incline.
  • From (3, 65), the graph drops back down to (4, 48) and continues with a lower slope.

Correct Equation

The piecewise function you've graphed is:

\[ y = \begin{cases} 15x + 20 & \text{if } 0 \leq x \leq 3 \ 12x & \text{if } x > 3 \end{cases} \]

This is the function that models the total cost of renting the bouncy house based on the number of hours rented.