document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=427435>Question 427435</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Suppose a company wants to do random drug testing of its employees and that 2% of the employees use illegal drugs. If the test for detecting drug use is given to people who use illegal drugs, it returns a positive result 99% of the time. When the test is given to people who do not use drugs, it returns a positive result 6% of the time. What is the probability that an employee who receives a positive test result actually does NOT use drugs? (hint..use a tree using \"user\" and \"non-user\" instead of \"ill\" and \"healthy\") Round to four decimal places. \r<BR>\n" );
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document.write( "There are 20 grapefruit in a basket. 9 are sweet, and 11 are sour. If you select 2 at random,what is the probability that they will all be sweet? (Round the answer to four decimal places.) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #297401 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=297401\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Suppose a company wants to do random drug testing of its employees and that <BR>\n" );
document.write( "2% of the employees use illegal drugs. <BR>\n" );
document.write( "If the test for detecting drug use is given to people who use illegal drugs, it returns a positive result 99% of the time. <BR>\n" );
document.write( "When the test is given to people who do not use drugs, it returns a positive result 6% of the time. <BR>\n" );
document.write( "What is the probability that an employee who receives a positive test result actually does NOT use drugs? <BR>\n" );
document.write( "(hint..use a tree using \"user\" and \"non-user\" instead of \"ill\" and \"healthy\") Round to four decimal places.<BR>\n" );
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document.write( "P(nonuse|+) = P(non AND +)/[P(+ AND non)+P(+ AND use)<BR>\n" );
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document.write( "= [P(+|non)*P(non)/[P(+|non)*P(non)+P(+|use)*P(use)<BR>\n" );
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document.write( "= [0.06*0.98]/[same + 0.99*0.02]<BR>\n" );
document.write( "= [0.0588]/[0.0588+0.0198]<BR>\n" );
document.write( "= 0.7481<BR>\n" );
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document.write( "There are 20 grapefruit in a basket. 9 are sweet, and 11 are sour. If you select 2 at random,what is the probability that they will all be sweet? (Round the answer to four decimal places.)<BR>\n" );
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document.write( "P(2 sweet) = 9C2/20C2 = 0.1895<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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document.write( " </SPAN>\n" );
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