Solution Found!
A civil engineer is analyzing the compressive strength of
Chapter 8, Problem 15E(choose chapter or problem)
A civil engineer is analyzing the compressive strength of concrete. Compressive strength is normally distributed with \(\sigma^{2}=1000(\mathrm{psi})^{2}\). A random sample of 12 specimens has a mean compressive strength of \(\bar{x}=3250\) psi.
(a) Construct a 95% two-sided confidence interval on mean compressive strength.
(b) Construct a 99% two-sided confidence interval on mean compressive strength. Compare the width of this confidence interval with the width of the one found in part (a).
Equation Transcription:
Text Transcription:
sigma^2=1000(psi)^2
x bar=3250
Questions & Answers
QUESTION:
A civil engineer is analyzing the compressive strength of concrete. Compressive strength is normally distributed with \(\sigma^{2}=1000(\mathrm{psi})^{2}\). A random sample of 12 specimens has a mean compressive strength of \(\bar{x}=3250\) psi.
(a) Construct a 95% two-sided confidence interval on mean compressive strength.
(b) Construct a 99% two-sided confidence interval on mean compressive strength. Compare the width of this confidence interval with the width of the one found in part (a).
Equation Transcription:
Text Transcription:
sigma^2=1000(psi)^2
x bar=3250
ANSWER:
Step 1 of 4
Given,
The standard deviation,
Sample size, n = 12.
The mean,
For a sample mean, 
