document.write( "Question 825783: The lifetime of a certain type of machine is normally distributed with mean=2.5 years, and standard deviation=1.4 years. If this type of machine is guaranteed for 1 year, approxiametly what fraction of original sales will require replacement? \n" ); document.write( "
Algebra.Com's Answer #497595 by stanbon(75887)\"\" \"About 
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The lifetime of a certain type of machine is normally distributed with mean=2.5 years, and standard deviation=1.4 years. If this type of machine is guaranteed for 1 year, approxiametly what fraction of original sales will require replacement?
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\n" ); document.write( "z(1) = (1-2.5)/1.4 = -1.07
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\n" ); document.write( "P(x < 1) = P(z < -1.07)
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\n" ); document.write( "Comment: Use a z-chart, software,
\n" ); document.write( "or calculator to find the area under
\n" ); document.write( "the normal curve to the left of z = -1.07
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\n" ); document.write( "I use a TI-84 calculator to get the following::\r
\n" ); document.write( "\n" ); document.write( "P(z < -1.07) = normalcdf(-100,-1.07) = 0.1423
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\n" ); document.write( "Ans: 1423/10,000
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H \n" ); document.write( "
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