Use a normal probability plot to assess whether the sample data could have come from a population that is normally distributed. O-Ring ThicknessĀ A random sample of O-rings was obtained, and the wall thickness (in inches) of each was recorded.

0.276 |
0.274 |
0.275 |
0.274 |
0.277 |

0.273 |
0.276 |
0.276 |
0.279 |
0.274 |

0.273 |
0.277 |
0.275 |
0.277 |
0.277 |

0.276 |
0.277 |
0.278 |
0.275 |
0.276 |

Answer :

Step 1 :

From the Excel

> arrange x - values in ascending order

> calculate , i is the position of the data

> find z score for each

> plot x - values on the horizontal axis and the corresponding z-score on the vertical axis

...x | position | = | Z - value |

0.273 | 1 | 0.030864 | -1.86824 |

0.273 | 2 | 0.080247 | -1.40341 |

0.274 | 3 | 0.12963 | -1.12814 |

0.274 | 4 | 0.179012 | -0.91914 |

0.274 | 5 | 0.228395 | -0.74414 |

0.275 | 6 |