30. Solving a chemistry problem

2. A sample of sodium chloride brand "chemically pure" was analyzed by various methods for the content of impurities of sulfates, phosphates, bromides and found in five parallel determinations. %: impurities of sulfate ions: 0.0004; 0.0005; 0.0006; 0.0007; 0.0008; phosphate ion impurities: 0.0008; 0.0009; 0.0010; 0.0012; 0.0014; bromide ion impurities: 0.0010; 0.0010; 0.0020; 0.0030; 0.0040. Calculate the confidence interval for the average content of these impurities at a confidence level P = 0.95. Answer: the confidence interval for the average content of sulfate ions is (0.0006 ± 0.0002)%, for phosphate ions - (0.0011 ± 0.0003)%, for bromide ions - (0.0020 ± 0.0016) %.