__A level C confidence interval for μ (Normal case: known σ__)

The level C is a value that the experimenter chooses to indicate the level of accuracy desired in the interval estimate. *z** is called the critical value. Its value is determined from the standard normal distribution for the specified level of C.

Confidence level C |
z* |

90% |
1.645 |

95% |
1.96 |

99% |
2.575 |