Eyestrain is thought to be associated with different types of office work. The A

Question

Eyestrain is thought to be associated with different types of office work. The Acme Temp-Help Company provides short-term employees to substitute for vacationing data entry personnel. Previous research has shown that approximately 21% of full time data entry personnel have eyestrain, and Acme would like to estimate the proportion, rt, of their 6,000 part-time data entry employees that have eyestrain. a) They would like to estimate n to within 0.05 with 95% confidence. If they accept the starting value of 0.21 as a reasonable initial estimate of n, what sample size should they use for their study? Suppose Acme had felt that the working conditions of their temporary data entry personnel were different enough that they should not depend on the 0.21 as an initial estimate. In a few sentences, explain how your procedure for choosing a samples size would differ from your solution in part (a). Recalculate a new estimate of the necessary sample size

Explanation / Answer

1)a)p=0.21 ; margin of error E =0.05 ; for 95% CI, z=1.96

hence sample size =p(1-p)(Z/E)2 =~255

b) for estimated p=0.5 ; sample size =~385

2)point estimate p=192/594=0.3232

std error =(p(1-p)/n)1/2 =0.019

and for 95% CI, z=1.96

hence confidence interval =mean -/+ z*Std error =0.2856 ; 0.3608

3)option a and e are correct

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