Question on errors in Prac report

[Reckoner]

So for physics we are doing a prac on bungee jumping, and I'm a bit unsure as to how to put in errors.

If for 3 trials I had measured 1.53m, 1.57m and 1.54m (all+-0.005), what would be the percentage error for the average length?

What I've done is find the  maximum difference between the measurements (0.04), then divided that by the average (1.55) to get a percentage error of +-2.58%.

Is this right? or should I take the maximum deviation from the average (0.03)? Do I incorporate the +-0.005?

Thanks 

[Phy124]

It was of my understanding to calculate a percentage error, you had to know the realistic or actual value, then you did:



When I did all my pracs we would work out all the measurements, get an average (etc.), then the teacher would give us the actual value and we would calculate the percentage error from that.

Although, I may be misinterpreting what you are asking.

[Reckoner]

That's not exactley what I meant, we have no "actual value". But don't worry, the problem has been solved (at least temporarily). This is how everyone else in my class is doing it, so I'm going to stay with it. Thanks anyway

[bafron]

you did it correctly