a)
If we look at the table closely, we see that we have a constant change of -3. Since every 1 week, 3 pounds are lost, we have a constant change of -3. The data is linear.
b)
The change is NOT constant every week.
First, change is -5
Next, change is -4
Then, change is -3
So, it is non-linear.
c)
The rate for week 1 - week 2 is constant at 168.
If we were to graph, we would have a horizontal line.
So, data is linear.