Problem 1 Assume that the helium porosity (in percentage) of coal samples taken from any particular seam is normally dis

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Problem 1 Assume That The Helium Porosity In Percentage Of Coal Samples Taken From Any Particular Seam Is Normally Dis 1 (144.41 KiB) Viewed 98 times

Problem 1 Assume that the helium porosity (in percentage) of coal samples taken from any particular seam is normally distributed with true standard deviation .75. a. Compute a 95% CI for the true average porosity of a certain seam if the average porosity for 20 specimens from the seam was 4.85. b. Compute a 98% CI for true average porosity of another seam based on 16 specimens with a sample average porosity of 4.56. c. How large a sample size is necessary if the width of the 95% interval is to be .40? d. What sample size is necessary to estimate true average porosity to within .2 with 99% confidence?