Here is one way to get a rough approximation:
is approximately .
I've been given a table of values and I have to estimate the instantaneous velocity at t = 2002. I can do this by averaging two secant lines, but it wants me to measure the slope of the tangent. Here's the table.
t | N
1996 | 44
1998 | 69
2000 | 109
2002 | 141
2004 | 182
2006 | 233
I really have no idea where to start.