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(a) Compute a 90% confidence interval for the true average porosity of a certain seam if the average porosity for 20 specimens from the seam was 4.85. 1 (b) How large a sample size is necessary if the width of the 95% interval for the true average is to be 0.30?

(a) Compute a 90% confidence interval for the true average porosity of a certain seam if the average porosity for 20 specimens from the seam was 4.85. 1 (b) How large a sample size is necessary if the width of the 95% interval for the true average is to be 0.30?

MATLAB: An Introduction with Applications
MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
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Assume that the helium porosity ( in percentage) of sample taken from any particular seam is normally distributed with true standard deviation of 0.75
(a) Compute a 90% confidence interval for the true average porosity of a certain seam if the average porosity for 20 specimens from the seam was 4.85. 1 (b) How large a sample size is necessary if the width of the 95% interval for the true average is to be 0.30?
Transcribed Image Text:(a) Compute a 90% confidence interval for the true average porosity of a certain seam if the average porosity for 20 specimens from the seam was 4.85. 1 (b) How large a sample size is necessary if the width of the 95% interval for the true average is to be 0.30?
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