Finding average acceleration from data points of a velocity time graph?

[TexasCow]

Well I posted this in the calculus section but think it would be answered easier here since it's mild calculus if any.

1. Homework Statement
I'm studying for a Calculus test and I am having trouble on a problem. And who better to ask than the members of physicsforums!?

Basically, we are studying average acceleration, velocity, secant and tangent lines. We are given the graph of a function, and its corresponding data points.

The question asks:
"Find the average acceleration of the car, in f/s, over the interval 0<t<50.(The inequality signs are acutally "less than or equal to", but I don't know how to input such characters.)

I'm aware that the derivative of a velocity time graph is its acceleration/time graph. So I assume that the slope of the line is the acceleration. Unfortunately, we are not permitted to fit a best line, or derive an equation. Is there another way of doing this? Thanks for any help.

 

[Chi Meson]

The average acceleration is simply the net change in velocity over the corresponding change in time. You just need to coordinates of the two data points at 0 and 50 s.

This is the easy one.

 

[TexasCow]

Wow, I just realized. I feel so dumb! Thanks a bunch.