Slope of the line indicates the direction and the steepness of the line.
The rate of change of the temperature of roast is changing(decreasing) 40 degrees Fahrenheit per hour.
What is the slope of the line?
Slope of the line indicates the direction and the steepness of the line. It can be given as,
[tex]m=\dfrac{y_2-y_1}{x_2-x_1}[/tex]
Here, [tex]x,y[/tex] are the coordinate points on which the line passes through.
Given information-
The initial temperature of roast is 185°F.
The temperature of room is 75°F.
The tangent line in the given graph passes through the one points (30,145).
The another point of the tangent line are (90,105).
As the two point of the curve we have. Thus the slope of the line passing through the point (30,145). and (90,105) can be given as,
[tex]m=\dfrac145-105{}{30-90}\\m=\dfrac{40}{-60}\\m\cong-0.667\rm F^o/min[/tex]
For an hour,
[tex]m=-0.667\times60\\m=-40\rm F^o/min[/tex]
Thus the rate of temperature of is changing 40 degrees Fahrenheit each hour. Here the negative sign indicates that the temperature of roast is decreasing with time.
Hence the rate of change of the temperature of roast is changing(decreasing) 40 degrees Fahrenheit per hour.
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