List the values of the displacement of the string at x = 4.0 m at 1 s intervals from t = 0 s to t = 6 s.

I attached the missing graph. 
I also made an animation of what would happen, you can play with the slider t to see how waves would propagate. The resulting amplitude is simply the sum of amplitudes of each wave at that point.
I will mark one wave with g for green and one with r for red.
With this animation, it won't be hard to figure out the results.

Link to the animation:
https://www.desmos.com/calculator/ivl8tv10rk

The purpose of a lab is to do your "expirements" the importance of the topic is so you can now what the story is about and the last one is because no one is me with my question ( what is 3 over 4 x - 9 = 27 maybe you can )