Hi everybody,

a composite object is weighted 3 times during 3 phases of its manufacturing process:

Now my question:

Under the supposition that all data are Normal Distributed, if I would describe the statistical distribution of the variable "Weight of painted object", which of the following Standard Deviation should I use?

Parcosan

a composite object is weighted 3 times during 3 phases of its manufacturing process:

- After object is
**trimmed** - After object has
**filler**applied - After object is
**painted**

**filler**and**painting**as difference of measured values:Sample ID | Measured weight after trimming [g] | Measured weight after filler [g] | Calculated weight of filler [g] | Measured weight after painting [g] | Calculated weight of painting [g] |
---|---|---|---|---|---|

1 | 2510 | 2710 | 2510-2710=200 | 2830 | 2830-2710=120 |

2 | 2630 | 2790 | 160 | 2900 | 110 |

3 | 2660 | 2950 | 290 | 3090 | 140 |

4 | 2620 | 2880 | 260 | 2990 | 110 |

5 | 2610 | 2720 | 110 | 2890 | 170 |

6 | 2600 | 2992 | 392 | 3060 | 68 |

7 | 2670 | 3170 | 500 | 3300 | 130 |

8 | 2660 | 2740 | 80 | 2870 | 130 |

9 | 2500 | 2790 | 290 | 2960 | 170 |

10 | 2630 | 2800 | 170 | 2992 | 192 |

Average | 2609 | 2854 | 245 | 2988 | 134 |

Standard Deviation | 59.34 | 145.90 | 129.63 | 137.43 | 36.10 |

Now my question:

Under the supposition that all data are Normal Distributed, if I would describe the statistical distribution of the variable "Weight of painted object", which of the following Standard Deviation should I use?

- The value of the 5th column:
*137.43* - The Standard Deviation calculated as sum of Standard Deviations of: weight of object trimmed+weight of filler+weight of painting: [math]\sigma_{after-inting}=\sqrt{\sigma_{after-trimming}^2 + \sigma_{filler}^2+ \sigma_{painting}^2}=\sqrt{59.34^2+129.63^2+36.10^2}= \bold{\textcolor{red}{147.06}}[/math]

Parcosan

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