Question

Consider a normal population distribution with the value of \( \sigma \) known. USE SALT (a) What is the confidence level for the interval \( \bar{x} \pm 2.88 \sigma / \sqrt{n} \) ? (Round your answer to one decimal place.) \( \square \) \( \% \) (b) What is the confidence level for the interval \( \bar{x} \pm 1.45 \sigma / \sqrt{n} \) ? (Round your answer to one decimal place.) \( \square \) \( \% \) (c) What value of \( z_{a / 2} \) in the CI formula below results in a confidence level of \( 99.7 \% \) ? (Round your answer to two decimal places.) \[ \begin{aligned} & \left(\bar{x}-z_{a / 2} \cdot \frac{\sigma}{\sqrt{n}}, \bar{x}+z_{a / 2} \cdot \frac{\sigma}{\sqrt{n}}\right) \\ z_{a / 2}= & \end{aligned} \] (d) Answer the question posed in part (c) for a confidence level of \( 70 \% \). (Round your answer to two decimal places.) \[ z_{a / 2}=\square \] You may need to use the appropriate table in the Appendix of Tables to answer this question.

          Consider a normal population distribution with the value of \( \sigma \) known.
USE SALT
(a) What is the confidence level for the interval \( \bar{x} \pm 2.88 \sigma / \sqrt{n} \) ? (Round your answer to one decimal place.)
\( \square \) \( \% \)
(b) What is the confidence level for the interval \( \bar{x} \pm 1.45 \sigma / \sqrt{n} \) ? (Round your answer to one decimal place.)
\( \square \) \( \% \)
(c) What value of \( z_{a / 2} \) in the CI formula below results in a confidence level of \( 99.7 \% \) ? (Round your answer to two decimal places.)
\[
\begin{aligned}
& \left(\bar{x}-z_{a / 2} \cdot \frac{\sigma}{\sqrt{n}}, \bar{x}+z_{a / 2} \cdot \frac{\sigma}{\sqrt{n}}\right) \\
z_{a / 2}= &
\end{aligned}
\]
(d) Answer the question posed in part (c) for a confidence level of \( 70 \% \). (Round your answer to two decimal places.)
\[
z_{a / 2}=\square
\]

You may need to use the appropriate table in the Appendix of Tables to answer this question.

Consider a normal population distribution with the value of σ known.
USE SALT
(a) What is the confidence level for the interval x̅± 2.88 σ / √(n) ? (Round your answer to one decimal place.)
□ %
(b) What is the confidence level for the interval x̅± 1.45 σ / √(n) ? (Round your answer to one decimal place.)
□ %
(c) What value of za / 2 in the CI formula below results in a confidence level of 99.7 % ? (Round your answer to two decimal places.)

(x̅-za / 2·(σ)/(√(n)), x̅+za / 2·(σ)/(√(n)))

za / 2=

(d) Answer the question posed in part (c) for a confidence level of 70 %. (Round your answer to two decimal places.)

za / 2=□

You may need to use the appropriate table in the Appendix of Tables to answer this question.

Added by Christopher B.

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