30. Solving a chemistry problem

1. When controlling the quality of the dosage form - enteric coated tablets of diclofenac sodium containing the declared (indicated on the package) mass of 25 mg of diclofenac sodium in one tablet, we tested the release of the pharmacologically active substance (i.e., diclofenac sodium) in 0.1 mol/l aqueous solution of HCI when keeping the tablets in this solution for a certain time under given conditions. In five parallel analyzes, it was found that in 120 minutes the following amount of diclofenac sodium passes into the solution, as a percentage of the declared mass:
8.3; 8.5; 8.8; 8.9, 9.1. Calculate the confidence interval W±ΔW of the average result of the determination at a confidence level P = 0.95. Answer: W±ΔW = ( 8.7 ± 0.4)%.