(Solved): A civil engineer is analyzing the compressive strength of concrete. Compressive strength is normal ...

A civil engineer is analyzing the compressive strength of concrete. Compressive strength is normally distributed with \( \sigma^{2}=1000 \) psi A random sample of 12 sample specimens has a mean compressive strength of \( \bar{x}=3247 \) psi. Round your answers to 1 decimal place. (a) Calculate the \( 95 \% \) two-sided confidence interval on the true mean compressive strength of concrete. \[ \leq \mu \leq \] (b) Calculate the \( 99 \% \) two-sided confidence interval on the true mean compressive strength of concrete. \[ \leq \mu \leq \]