Answer to Question #42056 in Statistics and Probability for surya

Question #42056

A civil engineer is analyzing the compressive strength of concrete. A random sample of 12 specimens has a mean compression strength of 3250 psi with variance 1000 (psi)2.
i) Construct a 95% confidence interval for the population mean compressive strength.
ii) Construct a 95% confidence interval for the population standard deviation of compressive strength.

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Assignment Expert

03.06.15, 20:13

Dear SSaa. We use Student's t-distribution instead of z-scores in this problem, because population standard deviation is not known in this problem and the sample size is small (n=12).

SSaa

01.06.15, 15:01

u should get the standard deviation that is the squre root of the variance and then proceed same process (1-(CI/100))=0.05 look for probability of 0.05/2=0.025 Z=1.96 ur ans will be mean (+,-) ((z*standard deviation) /sqrt(n) ) 3267.89 3232.107

Answer to Question #42056 in Statistics and Probability for surya

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