document.write( "Question 1033448: Find the z-scores that bound the middle 0.80 of the normal distribution\r
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Algebra.Com's Answer #648240 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Yes, it's asking for two z-scores, the left one will be\r\n" );
document.write( "negative and the right one positive.  They will have the\r\n" );
document.write( "same absolute value, since the normal curve is symmetrical\r\n" );
document.write( "about the y-axis.\r\n" );
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document.write( "The middle 0.80 of the normal curve has 0.10 to the left of it\r\n" );
document.write( "and 0.10 to the right of it.\r\n" );
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document.write( "If  you have a TI-83 or TI-84 calculator,\r\n" );
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document.write( "2ND VARS 3 for invNorm(.1,0,1) ENTER\r\n" );
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document.write( "Read z = -1.281551567, and by symmetry \r\n" );
document.write( "the upper z-score is +1.281551567\r\n" );
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document.write( "Maybe you're supposed to use a normal table.\r\n" );
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document.write( "There are two kinds of normal tables in use today.\r\n" );
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document.write( "If you are using a table that has negative z values,\r\n" );
document.write( "look in the body of the table for the closest value\r\n" );
document.write( "to 0.10 which is 0.1003 and it occurs where z=-1.28.\r\n" );
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document.write( "If you are using a table that reads from the middle,\r\n" );
document.write( "then look in the body of the table for the closest\r\n" );
document.write( "value to 0.40 (one half of 0.80), which is 0.3997, and\r\n" );
document.write( "it occurs where z=1.28.\r\n" );
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document.write( "Edwin
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