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3. A civil engineer is analyzing the compressive strength of concrete. Compressive strength is normally distributed with σ2 = 1000 (psi)2 . A random sample of 12 specimens has a mean compressive strength
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3. A civil engineer is analyzing the compressive strength of concrete. Compressive strength is normally distributed with σ2 = 1000 (psi)2 . A random sample of 12 specimens has a mean compressive strength of 3250 psi. (a) Construct a 95% two-sided confidence interval on the mean compressive strength. (b) Suppose it is desired to estimate the mean compressive strength with an error that is less than 15 psi at 99% confidence. What is the sample size required?

User Nihat
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Answer: a) 3232.1077 < u < 3267.8923

b) 3226.448 <u< 3273.552

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3. A civil engineer is analyzing the compressive strength of concrete. Compressive-example-1
User Gray Adams
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