To find the charge per minute, we can analyze the information given with the two points on the graph: (0, 15) and (50, 90).
-
The point (0, 15) indicates that when no minutes are used (x = 0), the total charge is $15. This means that the flat fee is $15.
-
The point (50, 90) indicates that when 50 minutes are used, the total charge is $90.
We can set up an equation for the total charge based on minutes used:
\[ \text{Total Charge} = \text{Flat Fee} + (\text{Charge per Minute}) \times (\text{Minutes Used}) \]
Let \( m \) be the charge per minute. Using the points:
From the first point (0, 15): \[ 15 = 15 + m \cdot 0 \quad \text{(which is true)} \]
From the second point (50, 90): \[ 90 = 15 + m \cdot 50 \]
Now, let's solve for \( m \): \[ 90 - 15 = m \cdot 50 \] \[ 75 = 50m \] \[ m = \frac{75}{50} = \frac{15}{10} = \frac{3}{2} = 1.5 \]
Thus, the charge per minute is:
\[ \text{The charge per minute is } $1.50. \]
You can also express this in terms of exact change as $1.50 if needed, or say it is 1 dollar and 50 cents.
1 answer