document.write( "Question 438329: A market researcher wants to find a confidence interval estimate of the mean age of all TCC students. A study done earlier in the year found that the standard deviation of all TCC student ages was 14.2 years. How large a random sample must the researcher take in order to be 95% confident that margin of error is 3.2 years.
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Algebra.Com's Answer #303167 by ewatrrr(24785) $\"\"$ $\"About$

You can put this solution on YOUR website!

 
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document.write( "Hi
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document.write( "A market researcher wants to find a confidence interval estimate of the mean
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document.write( " age of all TCC students. A study done earlier in the year found that the
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document.write( " standard deviation of all TCC student ages was 14.2 years. How large a random
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document.write( " sample must the researcher take in order to be 95% confident that margin of
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document.write( " error is 3.2 years.\r
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document.write( "ME = 1.96[14.2/sqrt(n)]
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document.write( " n = (1.96*14.2/ME)^2 = 1.96*14.2/3.2)^2 = 75.6465 
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document.write( "  Sample Size of 76 needed\r
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document.write( "re: 1.96
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document.write( "See Summary below of various critcal regions per confidence level:
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document.write( "	a	a/2	crtical regions	
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document.write( "90%	0.1	5%	z <-1.645	z >+1.645
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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<-2.575	z >+2.575
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