An operator is analyzing the structural strength of a cement mix. Structural strength is normally distributed σ2 = 1000 (psi)2 . What sample size is required if it is desired to estimate the structural strength with an an error less than 10 psi at 95% confidence level? Would the sample size increase or decrease if the confidence level become 90%.
An operator is analyzing the structural strength of a cement mix. Structural strength is normally distributed σ2 = 1000 (psi)2 . What sample size is required if it is desired to estimate the structural strength with an an error less than 10 psi at 95% confidence level? Would the sample size increase or decrease if the confidence level become 90%.
Chapter2: Loads On Structures
Section: Chapter Questions
Problem 1P
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An operator is analyzing the structural strength of a cement mix. Structural strength is normally distributed σ2 = 1000 (psi)2 . What sample size is required if it is desired to estimate the structural strength with an an error less than 10 psi at 95% confidence level? Would the sample size increase or decrease if the confidence level become 90%.
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e. Sample size required at 95% confidence level is 154
f. Sample size required at 95% confidence level is 39, reducing the confidence level to 90% decreases the sample size
g. None
h. Sample size required at 95% confidence level is at 39 %. reducing the confidence level to 90% will increase the sample sizes for the error to be less than 10
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