Question 93270
Assuming that the standard deviation of the number of hours worked by college graduates is 6.00 hours per week, what is the minimum sample size needed in order for us to be 95%confident that our estimate is within 1.2 hours per week of ? 
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n = [z's/E]^2
For 95% confidence z' = 1.96
s is the sample standard deviation = 6
E is the standard error = 1.2
n is the desired sample size
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n = [1.96*6/1.2]^2 = 96
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Cheers,
Stan H.