Permeability of sandstone during weathering. Refer to the Geographical Analysis (Vol. 42, 2010) study of the decay properties of sandstone when exposed to the weather, Exercise 2.69 (p. 91). Recall that slices of sandstone blocks were tested for permeability under three conditions: no exposure to any type of weathering (A), repeatedly sprayed with a 10% salt solution (B), and soaked in a 10% salt solution and dried (C). Measures of variation for the permeability measurements (mV) of each sandstone group are displayed in the accompanying MINITAB printout.

a. Find the range of the permeability measurements for group A sandstone slices. Verify its value using the minimum and maximum values shown on the printout.

b. Find the standard deviation of the permeability measurements for group A sandstone slices. Verify its value using the variance shown on the printout.

c. Which condition (A, B, or C) has the more variable permeability data?

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Variable Descriptive Statistics: PermA, PermB, PermC N StDev Variance Minimum Maximum Range PermA 100 14.48 209.53 55.20 122.40 67.20 PermB 100 21.97 482.75 50.40 150.00 99.60 PermC 100 20.05 401.94 52.20 129.00 76.80