To determine the additional charge per minute based on the points given (0, 15) and (50, 90) on a graph of cost versus minutes, we can calculate the slope of the line that connects these two points.
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Identify the points:
- Point A: (0, 15)
- Point B: (50, 90)
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Using the formula for slope (\(m\)): \[ m = \frac{y_2 - y_1}{x_2 - x_1} \] Where \((x_1, y_1) = (0, 15)\) and \((x_2, y_2) = (50, 90)\):
\[ m = \frac{90 - 15}{50 - 0} = \frac{75}{50} = 1.5 \]
The slope of the line represents the charge per minute. Thus, the company charges $1.50 per minute.
To confirm, we can also look at the total cost difference relative to the minutes:
- At 0 minutes, the cost is $15 (the fixed fee).
- At 50 minutes, the total cost is $90.
The total additional charge for 50 minutes is: \[ 90 - 15 = 75 \]
The charge per minute then is: \[ \frac{75}{50} = 1.5 \]
Thus, the fee the company charges per minute is indeed $1.50.
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