Answer:
[tex]\boxed{\text{(a) 4.0 Cal; (b) 4.0}}[/tex]
Step-by-step explanation:
(a) Calories per minute
The number of calories Sam is burning per minute is the number of calories divided by the number of minutes.
Start at the origin and move to the right to, say, 20 min.
Then go straight up until you hit the line of the graph.
From there, move left horizontally until you hit the y-axis.
Read the number of calories (80).
[tex]\begin{array}{rcl}\text{Calories per minute}& = & \dfrac{\text{Number of calories}}{\text{Number of minutes}}\\\\& = & \dfrac{\text{80 cal}}{\text{20 min}}\\\\& = & \textbf{4.0 cal/min}\\\\\end{array}\\\text{In 1 min Sam burns $\boxed{\textbf{4.0 Cal}}$}[/tex]
(b) Slope of graph
[tex]\text{Slope} = \dfrac{\Delta y}{\Delta x} =\dfrac{\text{Calories}}{\text{Minutes}} =\dfrac{\text{80 cal}}{\text{20 min}} = \textbf{4.0 cal/min}\\\\\text{The slope of the graph is $\boxed{\textbf{4.0}}$}[/tex]
