document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=507367>Question 507367</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 7.   Among companies doing highway or bridge construction, 80% test employees for substance abuse (based on data from the Construction Financial Management Association) A study involves the random selection of 12 such companies.\r<BR>\n" );
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document.write( "(a) Find the probability that exactly 7 of the 12 companies test for substance abuse.\r<BR>\n" );
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document.write( "(b) Find the probability that at least half of the companies test for substance abuse.\r<BR>\n" );
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document.write( "(c) For such group of 12 companies, find the mean and standard deviation for the number (among 12) that test for substance abuse.\r<BR>\n" );
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document.write( "(d) Using the results from part (c) and the range rule of thumb, indentify the range of usual value.\r<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #340446 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=340446\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Among companies doing highway or bridge construction, 80% test employees for substance abuse (based on data from the Construction Financial Management<BR>\n" );
document.write( "Association) <BR>\n" );
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document.write( "A study involves the random selection of 12 such companies.<BR>\n" );
document.write( "Binomial Problem with n = 12 and p = 0.8<BR>\n" );
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document.write( "(a) Find the probability that exactly 7 of the 12 companies test for substance abuse.<BR>\n" );
document.write( "P(x = 7) = 12C7(0.8)^7*(0.2)^5 = 0.0532<BR>\n" );
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document.write( "(b) Find the probability that at least half of the companies test for substance abuse.<BR>\n" );
document.write( "P(7<= x <=12) = 1 - P(0<= x <=6) 1 - binomcdf(12,0.8,6) = 0.9806<BR>\n" );
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document.write( "(c) For a group of 12 companies, find the mean and standard deviation for the number (among 12) that test for substance abuse.<BR>\n" );
document.write( "mean = np = 12*0.8 = 7.2<BR>\n" );
document.write( "std = sqrt(npq) = sqrt(7.2*0.2) = 1.2 <BR>\n" );
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document.write( "(d) Using the results from part (c) and the range rule of thumb, indentify the range of usual value.<BR>\n" );
document.write( "If the \"range of usual values\" is 6*std, you get 6*1.2 = 7.2 <BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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