It is always prudent for an analyst to perform a calibration check to ensure that there are no significant errors in the analysis. A calibration check involves analyzing an accurate standard of known concentration in conjunction with the samples.

A zinc calibration curve was measured the absorbance was found to be A=0.931Zn, ppm.

A calibration standard was accurately prepared to contain 0.28 ppm Zn. This calibration standard was subsequently analyzed and its absorbance was A = 0.264.

Calculate the % Relative Error.

Report the error to one decimal place. (Note for canvas: If relative %E is negative, report result with a sign (-) in front of the value (e.g. -10.5), do not use absolute)