document.write( "Question 481140: If you want to be 95% confident of estimating the population mean to within a sampling error of + or - 2, the standard deviation is assumed to be 13, what is the required sample size?\r
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Algebra.Com's Answer #329485 by ewatrrr(24785)\"\" \"About 
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document.write( "Hi,
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document.write( "95% confident of estimating the population mean to within a sampling error of ± 2
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document.write( "ME = 1.96\"alpha%2Fsqrt%28n%29\"
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document.write( "2 = 1.96\"13%2Fsqrt%28n%29\"
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document.write( "\"sqrt%28n%29+=+1.96%2A13%2F2\"
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document.write( "     n = (1.96*13/2)^2
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document.write( "     n = 162.3076, 163 rounded up\r
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document.write( "	a	a/2	crtical regions	
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document.write( "80%	0.2	10%	z <-1.28155	z >+1.28155
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document.write( "90%	0.1	5%	z <-1.645	z >+1.645
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document.write( "92%	0.8	4%	z <-1.751	z >+1.751
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document.write( "95%	0.05	2.50%	z <-1.96	z >+1.96
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document.write( "98%	0.02	1%	z <-2.33	z >+2.33
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document.write( "99%	0.01	0.50%	z<-2.576	z >+2.576
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