Objective:

Your boss wants to know the limits of expected variation. You know there is another shipment coming in next week and based upon this week's run, and assuming that the process is normally distributed, you can calculate/predict the limits of expected variation by calculating the mean and standard deviation for this data and then using the properties of the normal distribution to estimate the limits of the expected variation.

Instructions for you:

Using the data below:

1.  Calculate the average for length.

2.  Calculate the standard deviation for length.

3.  From these calculations, determine the expected variation. ( Use + or - 3 sigma)

You may complete this assignment by hand, as taught in the lecture. You may use Excel, or you may use a calculator or other software. We explain the fundamentals of the calculations, so that you learn the mechanics and the meaning of standard deviation. This basic approach gives you an understanding of standard deviation, which then allows you to be flexible in the tools that you use.

Data:

Data Length

10.67

10.74

10.68

10.72

10.66

10.69

10.70

10.72

10.69

10.68

10.72

10.70

10.70

10.73

10.75

10.73

10.69

10.68

10.70

10.77

10.72

10.69

10.66

10.69

10.63

10.68

10.73

10.74

10.65

10.69

10.70

10.72

10.75

10.71

10.72

St Dev

Upper Spec

Lower Spec

Target

ROUND ALL FINAL RESULTS TO 6 DECIMAL PLACES.

Mean for LENGTH:                        10.702857

Standard deviation for LENGTH: 0.030541

What is the lowest point of expected variation? 10.611233

What is the upper point of expected variation? 10.794481