Gas chromatography is a sensitive technique used by chemists to measure small amounts of compounds. The response of a gas chromatograph is calibrated by repeatedly testing specimens containing a known amount of the compound to be measured. A calibration study for a specimen containing 1 nanogram (ng) (that's 10-9 gram) of a compound gave the following response readings:

21.6 20.0 25.0 21.9

The response is known from experience to vary according to a normal distribution unless an outlier indicates an error in the analysis.

Question

Gas chromatography is a sensitive technique used by chemists to measure small amounts of compounds. The response of a gas chromatograph is calibrated by repeatedly testing specimens containing a known amount of the compound to be measured. A calibration study for a specimen containing 1 nanogram (ng) (that's 10-9 gram) of a compound gave the following response readings: 

21.6   20.0   25.0   21.9

The response is known from experience to vary according to a normal distribution unless an outlier indicates an error in the analysis.

anonymous · Answer

Estimate the mean response to 1 ng of this substance and give the margin of error for your choice of confidence level. then explain to a chemist who knows no statistics what your margin of error means