The black curve is represented by the function:
[tex]P(t)=12.643(1.0027)^t[/tex]
Then, for the first point at t = 1000, which is very close to the function, we can aproximate it to (1000,P(1000) = (1000,187)
We also can take the last point, close to the intersection of a vertical line with a horizontal line at (2000,6000)
Then, we can calculate the rate of chage: (6000 - 187)/(2000 - 1000) = 5813/1000 = 5.8 (rounded)
