document.write( "Question 1162533: A dangerous computer virus attacks a folder consisting of 250 files. Files
\n" ); document.write( "are affected by the virus independently of one another. Each file is
\n" ); document.write( "affected with the probability 0.032. What is the probability that more than
\n" ); document.write( "7 files are affected by this virus?
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Algebra.Com's Answer #786344 by Edwin McCravy(20055) $\"\"$ $\"About$

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A dangerous computer virus attacks a folder consisting of 250 files. Files
\n" ); document.write( "are affected by the virus independently of one another. Each file is
\n" ); document.write( "affected with the probability 0.032. What is the probability that more than
\n" ); document.write( "7 files are affected by this virus?
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document.write( "n is your sample size, 250\r\n" );
document.write( "p is your given probability, 0.032\r\n" );
document.write( "q is 1  -  p, q = 1 - 0.032 = 0.968  \r\n" );
document.write( "When n∙p and n∙q are greater than 5, you can use the normal approximation\r\n" );
document.write( "to the binomial to solve a problem.\r\n" );
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document.write( "n∙p = 250∙0.032 = 8 and n∙p = 250∙0.968 = 242, and they are both greater\r\n" );
document.write( "than 5, so we can use the normal approximation to the binomial.\r\n" );
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document.write( "On your TI-84, press 2ND VARS 2\r\n" );
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document.write( "       normalcdf \r\n" );
document.write( "lower:7\r\n" );
document.write( "upper:1E99     <--to get the \"E\", press 2ND and then the comma key.\r\n" );
document.write( "μ:8\r\n" );
document.write( "σ:2.78894341\r\n" );
document.write( "paste          <--scroll to highlight \"paste\" using down arrow key.\r\n" );
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document.write( "Press enter\r\n" );
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document.write( "See this:\r\n" );
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document.write( "normalcdf(7,1E99,8,2,2.78804341)\r\n" );
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document.write( "Press enter\r\n" );
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document.write( "See this:\r\n" );
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document.write( "0.6400806277    <--answer, round to 0.64\r\n" );
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document.write( "Edwin

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