The article "Simulation of the Hot Carbonate Process for Removal of CO2 and H2S from Medium Btu Gas" (K. Park and T. Edgar, Energy Progress, 1984:174-180) presents an equation used to estimate the equilibrium vapor pressure of CO2 in a potassium carbonate solution. The actual equilibrium pressure (in kPa) was measured in nine different reactions and compared with the value estimated from the equation. The results are presented in the following table:


Find a 95% confidence interval for the mean difference between the estimated and actual pressures.