A one-sided confidence interval can be found for a mean by using

or

where ta is the value found under the row labeled One tail. Find two one-sided 95% confidence intervals of the population mean for the data shown, and interpret the answers. The data represent the daily revenues in dollars from 20 parking meters in a small municipality.

2.60 |
1.05 |
2.45 |
2.90 |

1.30 |
3.10 |
2.35 |
2.00 |

2.40 |
2.35 |
2.40 |
1.95 |

2.80 |
2.50 |
2.10 |
1.75 |

1.00 |
2.75 |
1.80 |
1.95 |

Solution:

Step 1 of 2:

The given data is

X |

2.6 |

1.3 |

2.4 |

2.8 |

1 |

1.05 |

3.1 |

2.35 |

2.5 |

2.75 |

2.45 |

2.35 |

2.4 |

2.1 |

1.8 |

2.9 |

2 |

1.95 |

1.75 |

1.95 |

= 43.5 |

We have to find two one-sided 95% confidence intervals of the population mean.