Given the following table:

x	0.0026	0.0027	0.0028	0.0029	0.003
f(x)	0.97373123	-0.33118838	-0.84077079	-0.67988492	0.31884634

Calculate the value of $f'(0.0028)$ = to two places of accuracy.

To obtain more precise information about the value of $f$ near $0.0028$ enter a new increment value for $x$ here and then press the Submit Answer button.

How will you tell when your increment is small enough to give you a good answer for the problem?