document.write( "Question 272306: 1. Find the critical value zc necessary to form a confidence interval at 97% level of confidence \n" ); document.write( "
Algebra.Com's Answer #199238 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "This asks for the middle 97% or 0.97 of the data.  Half of \r\n" );
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document.write( "the middle 0.97 is to the right of z=0, and the other part\r\n" );
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document.write( "is to the left of z=0 on the graph  Half of 0.97 is 0.485.\r\n" );
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document.write( "We look through the BODY of the normal table at this site\r\n" );
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document.write( "http://business.statistics.sweb.cz/normal.jpg  \r\n" );
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document.write( "which should be just like the normal table in your book.\r\n" );
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document.write( "You will find the listing 0.4850 near the bottom of the table\r\n" );
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document.write( "on the right.  You will notice at the far left of the row\r\n" );
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document.write( "in which you find 0.4850 is the z value 2.1 and at the top of \r\n" );
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document.write( "the column in which you find 0.4850 you'll find the value 0.07. \r\n" );
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document.write( "You add those two numbers together 2.1+0.07 and get z=2.17. \r\n" );
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document.write( "You know by symmetry of the normal curve, that the other half of \r\n" );
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document.write( "the middle 97% is from z=-2.17 to z=0.  So the critical values\r\n" );
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document.write( "are z=-2.17 and z=2.17\r\n" );
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document.write( "Edwin
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