Finding determinate source of error

Question

An analyst applies the neutralization titration method to determine the amount of NaHCO3 in an antacid tablet. Before the measurement, the analyst checks the method by titrating a standard sample that is 98.76 %(w/w) NaHCO3. The results shown below represent five replicate determinations of the NaHCO3 in the standard sample. Is there a determinate source of error that affects the analysis at the 95% confidence level? % (w/w) NaHCO3 : 98.71% 98.59% 98.62% 98.44% 98.58%

Answer 1

Calculate the t value of the set of data using avg=98.59, s=0.097,n=5, Df=4

t=X-u/s/sqrt 5 = 4.14.

the critical value for t at 0.05/2,4 (two tailed t test ) is 2.78

since the calculated value of 4.14 exceeds the critical value of t we reject the null hypothesis and conclude that the average is different than the theoretical value at the95% CI