The 95% confidence interval for a quality control specimen is 9.2-10.2 mg/dl.
My question is, how do I figure out the coefficient of variation (%CV) with only this information?
Formula:
%CV = (SD/mean)100
You will need the mean and standard deviation. The mean is found by adding the two numbers and dividing by 2 (the mean is the middle of the confidence interval). 95% confidence interval is 2 standard deviations about the mean. You need to determine the value of 1 standard deviation, which in this case, would be 0.25 (you can determine this value by taking the difference between the mean and either number and dividing by 2).
I'll let you take it from here to calculate %CV using the formula above.