31. Solving a chemistry problem

2. When permanganatometrically determining the mass of iron (II) in the analyzed solution with a volume of 25 ml in five parallel analyzes, the concentration of iron (II) in the analyzed solution was found to be equal, mol/l: 0.0319; 0.0320; 0.0322; 0.0324; 0.0326. Calculate for the mass of iron (II) in the analyzed solution the standard deviation, the confidence interval and the relative error in determining the average mass at a confidence level Р=0.95.