document.write( "Question 734582: Please help. I'm not understanding this questions\r
\n" ); document.write( "\n" ); document.write( "The scores on a national test were normally distributed with a mean of 83 and a standard deviation of 8\r
\n" ); document.write( "\n" ); document.write( "To the nearest percent, what percentage of test takers scored between 70 and 90\r
\n" ); document.write( "\n" ); document.write( "15% of test takers scored below what test score? (Round to nearest test score) \n" ); document.write( "
Algebra.Com's Answer #449039 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
The scores on a national test were normally distributed with a mean of 83 and a standard deviation of 8
\n" ); document.write( "To the nearest percent, what percentage of test takers scored between 70 and 90
\n" ); document.write( "z(70) = (70-83)/8 = -13/8
\n" ); document.write( "z(90) = (90-83)/8 = 7/8
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\n" ); document.write( "P(70< x <90) = P(-13/8 < z < 7/8) = normalcdf(-13/8,7/8) = 0.7571 = 75.71%
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\n" ); document.write( "15% of test takers scored below what test score? (Round to nearest test score)
\n" ); document.write( "Draw the picture:
\n" ); document.write( "Find the z-score with a left tail of 15%
\n" ); document.write( "invNorm(0.15) = -1.0364
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\n" ); document.write( "Find the corresponding score value:
\n" ); document.write( "x = z*s + u
\n" ); document.write( "x = -1.0364*8+83 = 74.71
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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