In an experiment measuring the rate of absorption (in g/min-…
In an experiment measuring the rate of absorption (in g/min-cm2) two samples were obtained. For a sample of 9 clay bricks with fine glass particles added, the sample mean was 1299.3 with a sample standard deviation of 329.5. For a sample of 9 clay bricks without added glass particles, the sample mean was 4500.3 with a sample standard deviation of 271.4. The population variances of each group are assumed to be equal. To construct a confidence interval (under normal regularity conditions) of the difference of the two means, a critical value from which distribution would be used in the calculation?