Math Problem Statement

Arianys is going to use a computer at an internet cafe. The cafe charges an initial fee to use the computer and then an additional price per minute of usage. Let C represent the total cost of using a computer for t minutes at the internet cafe. A graph of C is shown below. Write an equation for C then state the slope of the graph and determine its interpretation in the context of the problem.

Solution

The problem describes a linear relationship between the total cost, CC, and the number of minutes, tt, spent using a computer at an internet cafe. Based on the graph, I can extract the following information:

  1. Equation for CC: The graph starts at C=9C = 9 when t=0t = 0, indicating that there is a fixed initial fee of $9$. As the number of minutes increases, the total cost CC increases linearly. From the graph, it appears that for every 5-minute increase, the cost increases by $5 (from $9 to $14 and $14 to $19).

    Thus, the equation of the line can be expressed as: C=9+1tC = 9 + 1 \cdot t where 99 is the initial cost, and 11 is the slope (the cost per minute).

  2. Slope of the Graph: The slope of the graph, mm, is calculated as: m=Change in CostChange in Time=14950=1m = \frac{\text{Change in Cost}}{\text{Change in Time}} = \frac{14 - 9}{5 - 0} = 1 This means that the cost increases by $1 for every additional minute used.

  3. Interpretation of the Slope: The slope of the graph (1) represents the rate at which the total cost increases with each additional minute. In the context of the problem, it indicates that the internet cafe charges $1 per minute after the initial fee.

Would you like to see further details or have any questions?

Related Questions:

  1. What would the total cost be if Arianys used the computer for 15 minutes?
  2. How would the equation change if the initial fee increased by $3?
  3. What is the significance of the y-intercept in the graph?
  4. How can the equation be used to predict the cost for 30 minutes?
  5. What would happen to the slope if the per-minute cost was reduced to $0.50?

Tip: To find the equation of a line given a graph, identify the y-intercept and calculate the slope using any two points on the line.

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Slope-Intercept Form

Formulas

y = mx + b

Theorems

Slope Formula

Suitable Grade Level

Grades 6-8