The void volume within a textile fabric affects comfort flam

The void volume within a textile fabric affects comfort, flammability, and insulation properties. Permeability of a fabric refers to the accessibility of void space to the flow of a gas or liquid. An article gave summary information on air permeability (cm^3/cm^2/sec) for a number of different fabric types. Consider the following data on two different types of plain-weave fabric: Assuming that the porosity distributions for both types of fabric are normal, let\'s calculate a confidence interval for the difference between true average porosity for the cotton fabric and that for the acetate fabric, using a 95% confidence level. Before the appropriate t critical value can be selected, df must be determined: Thus we use v = 9; the appendix table for critical values for t Distributions gives t_0.025 9 = 2.262. The resulting interval is With a high degree of confidence, we can say that true average porosity for triacetate fabric specimens exceeds that for cotton specimens by between

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