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A study revealed that an average expenditure by 30 Tuskegee students was $25. The reported standard...

A study revealed that an average expenditure by 30 Tuskegee students was $25. The reported standard deviation of expenditure was $6. How large a sample is needed to find the population mean within $2 at 92% confidence?

Math   Statistics-And-Probability   
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Answer #1

Solution :

Given that,

standard deviation = = 6

margin of error = E = 2

At 92% confidence level the z is ,

= 1 - 92% = 1 - 0.92 = 0.08

/ 2 = 0.08 / 2 = 0.04

Z/2 = Z0.04 = 1.751

Sample size = n = ((Z/2 * ) / E)2

= ((1.751 * 6) / 2)2

= 27.59

   = 28

Sample size = 28

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