Calculate the average speed from a bar graph

[Jath]

Well I need to calculate the average speed from a bar graph and I do believe it said percent difference, then find the percent difference from the bar graph to my line graph. All I have is pictures of the bar graph, so can someone please tell me how to find the average speed and the percent difference? If you can thanks a lot. Sorry for the crappy pictures too.

http://s3.photobucket.com/albums/y71/Jath/?action=view&current=Physics1.jpg
http://s3.photobucket.com/albums/y71/Jath/?action=view&current=Physics2.jpg

 

[Astronuc]

It's difficult to understand the two graphs. There are 8 bars in one and 6 in the other. Do they represent the same time intervals, such that each bar has equal weight.

Assuming one has N quantities v_i, then how does one determine the average value?

Then with the average value, take each v_i, subtract the average, which will give the difference between the particular value and the average. How would one then determine the percent difference?

http://www.ugrad.math.ubc.ca/coursedoc/math101/notes/applications/average.html

http://en.wikipedia.org/wiki/Arithmetic_mean

 

[Jath]

Very sorry about that. The first picture on the left the numbers represent distance(cm) and the second picture represent the speed (cm/s). With the first picture too, the 2 strips that are the same length are the second and third from the left on the second picture. Right now this is velocity and it is testing with a spark generator(I think that's what it was). In lab we threaded this tape, a meter long, through the spark generator and tried to walk at a constant speed. Measured from 0-6(the dots created by the spark generator), 0-12, 0-18, 0-24, all the way up to 60 and then cut them at 6, 12, 18, 24, etc. Taped them onto this bar graph and now I got to find out the average speed and percent difference between this and the line graph I made. All I need is an equation there, I hope.