In our Lot of 500 gadgets we divided the Range by 6 to get the Standard Deviation. In that case we were measuring a Population. We can’t do that with Samples of 5 because we had 500 chances of getting some of the extreme values - not just 5 chances. In Sa
This shows that by taking relatively small samples we can Estimate two very important things about the Distribution of the Measurements of any product: The Average and the Standard Deviation.
s = sigma = Standard Deviation
The Standard Deviation (s) of the gadgets is 0.3mm and the Average is 20.00mm. Knowing these 2 values, we can now put some % figures on our Normal Distribution Curve. If we’re doing a good job of cutting the gadgets to the Average of 20mm, 68% should be
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