SOLUTION: Plastic sheets produced by a machine periodically monitored for possible fluctuations in thickness. If the true variance in thicknesses exceeds 2.25 square milli- meters, there is

Question 1159702: Plastic sheets produced by a machine periodically monitored for possible fluctuations in thickness. If the true variance in thicknesses exceeds 2.25 square milli- meters, there is cause for concern about product quality. Thickness measurements for random sample 10 sheets produced in a particular shift were taken, giving the following results (in millimeters): 226 226 232 227 225 228 225 228 229
a. Find the sample variance.
Found 2 solutions by Boreal, ikleyn:
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
There are 9 values, not 10.
The mean is 227 1/3
sd is 2.236
variance is 5 mm^2
Answer by ikleyn(52781) (Show Source): You can put this solution on YOUR website!

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