<PRE><B>Question 339021</B>
 Assuming that the standard deviation of the number of hours worked by college graduates is 6.20 hours per week, what is the minimum sample size needed in order for us to be 90% confident that our estimate is within 1.2 hours per week of ?
Carry your intermediate computations to at least three decimal places. Write your answer as a whole number (and make sure that it is the minimum whole number that satisfies the requirements
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n = [zs/E]^2
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n = [invNorm(0.95)*6.2/1.2]^2
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n = [1.645*6.2/1.2]^2
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n = 73 when rounded up to the nearest whole number
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Cheers,
Stan H.</PRE>