Question

A shipment of ball bearings with a mean diameter of 25 mm and a standard deviation of 0.2 mm is normally distributed. By how many standard deviations does a ball bearing with a diameter of 25.6 mm differ from the mean? 0.6 1 2 3

Answer 1

You need to calculate how many times the required difference is of the standard deviation, i.e. the ratio difference / standard deviation.


These are the calculations:


Standard deviation = 0.2 mm


Difference between 25.6mm and the mean = 25.6mm - 25mm = 0.6 mm


Ratio difference / standard deviation = 0.6mm / 0.2 mm = 3.


Then, the answer is that a ball with a diameter of 25.6 mm differs 3 standard deviations from the mean.