A sample of Chrome moly drive shafts are pulled from a produ

A sample of Chrome moly drive shafts are pulled from a production line and the following statistics are determined. The sample has a mean of 118 kg and standard deviation of 16 kg. Each one is marked with its z-score from the quality assurance department. You pick up one of the shafts and the z-score is 1.29.    What is the actual measured mass of this shaft?

Solution

z = (X-mu) /sigma

=>1.29= (X - 118) / 16

=> (X - 118) = 20.64

=> X = 138.64kg

Therefore , actual mass of shaft = 138.64kg Answer