Algebra.Com's Answer #155820 by Edwin McCravy(20060)![\"\"](\"/images/stars/stars-13.gif\")  
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Using the z-table (Table E), find the critical value (or values) for a a=.018 left-tailed test.
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document.write( "We need to find a cut off point on the left of the curve, like\r\n" );
document.write( "the black line segment below:\r\n" );
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document.write( "so that the area under the curve to the left of that cut-off\r\n" );
document.write( "point will be .018. \r\n" );
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document.write( "However table E only gives the areas between the y-axis and the\r\n" );
document.write( "cut-off point. Since there is area of .5 on the whole left side\r\n" );
document.write( "of the y-axis, and there is to be area .018 to the left of that\r\n" );
document.write( "cut-off point, then there will be area of .5-.018 or .482 between\r\n" );
document.write( "the y-axis and the cut-off point. So we look in the BODY of the\r\n" );
document.write( "table, until we find the closest value to .482. The closest value\r\n" );
document.write( "in Table E to .482 is .4821. We find that value where you see 2.1\r\n" );
document.write( "under the z-column and .00 at the top of the column .4821 is in.\r\n" );
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document.write( "So the answer is z = -2.1. You have to make it negative because it\r\n" );
document.write( "is a left-tail test and the numbers are negative on the left side\r\n" );
document.write( "of the curve.\r\n" );
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document.write( "Edwin \n" );
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