SOLUTION: Managers at an automobile manufacturing plant would like to estimate the mean completion time of an assembly line operation, μ. The managers plan to choose a random sample of com
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Question 1142560: Managers at an automobile manufacturing plant would like to estimate the mean completion time of an assembly line operation, μ. The managers plan to choose a random sample of completion times and estimate μ via the sample. Assuming that the standard deviation of the population of completion times is 10.1 minutes, what is the minimum sample size needed for the managers to be 99% confident that their estimate is within 1.7 minutes of μ? Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! The 99%CI would be z(0.995)*sigma/sqrt(n), and that has to be < 1.7
so 2.576*10.1/sqrt(n) <1.7
square both sides
676.916/n < 2.89
so 676.916/2.89
or n > 676.916/2.89
n>234.22 or 235
