document.write( "Question 933491: For a normal distribution with µ = 500 and σ = 100, find the following values:
\n" ); document.write( "a. What X value separates the highest 10% of the distribution from the rest of the scores?
\n" ); document.write( " b. What X values form the boundaries for the middle 60% of the distribution?
\n" ); document.write( " c. What is the probability of randomly selecting a score greater than X = 475?\r
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Algebra.Com's Answer #566893 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
For a normal distribution with µ = 500 and σ = 100, find the following values:
\n" ); document.write( " a. What X value separates the highest 10% of the distribution from the rest of the scores?
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\n" ); document.write( "Find the z-value with a 10% right tail:: invNorm(0.10) = 1.2816
\n" ); document.write( "Find the corresponding X-value:: X = 1.2816*100+500 = 628.16
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\n" ); document.write( " b. What X values form the boundaries for the middle 60% of the distribution?
\n" ); document.write( "Find the z-value with a left tail of 20%:: invNorm(0.20) = -0.8416
\n" ); document.write( "Lower boundary:: X = -0.8416*100+500 = 500-84.16 = 415.84
\n" ); document.write( "Upper boundary:: X = +0.8416*100+500 = 500+84.16 = 584.16
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\n" ); document.write( " c. What is the probability of randomly selecting a score greater than X = 475?
\n" ); document.write( "z(475) = (475-500)/100 = -25/100 = -0.25
\n" ); document.write( "P(X > 475) = P(z > -0.25) = normalcdf(-0.25,100) = 0.5987
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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