confidence intervals and lower/upper error bars

Hi,

I need help finding the correct upper and lower confidence intervals for a small data set I have (see attached). In the data sheet I have errors in locations that a system has returned to me e.g. the system returned a value 52.57m away from where the object is actually located etc.

I want to graph the location accuracy. Any location with an error greater than 55m has 0% accuracy. Obviously if no error is incurred, it’s 100% accurate.
In the calculation worksheet I worked out the average error in meters, then calculated it as a percentage (relative to the 55m threshold) and minused from 100% to get the mean accuracy. However now I want to plot the 95% confidence interval bars.

I’m getting confused as to how I can do this without distorting the values as I need the error bars in percentages but the standard deviation passed to the confidence function is based on meters.

Can anyone please advise or show me how to do this?

Thanks in advance.