Assume that the helium porosity (in percentage) of coal samplestaken from any particular
Chapter 7, Problem 5(choose chapter or problem)
Assume that the helium porosity (in percentage) of coal samplestaken from any particular seam is normally distributedwith true standard deviation .75.a. Compute a 95% CI for the true average porosity of a certainseam if the average porosity for 20 specimens fromthe seam was 4.85.b. Compute a 98% CI for true average porosity of anotherseam based on 16 specimens with a sample average porosityof 4.56.c. How large a sample size is necessary if the width of the95% interval is to be .40?d. What sample size is necessary to estimate true averageporosity to within .2 with 99% confidence?
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